Evaluation of the ability of natural and synthetic scaffolds in providing an appropriate environment for growth and chondrogenic differentiation of adipose-derived mesenchymal stem cells

Background:

Although progenitor cells have been observed in articular cartilage, this part has a limited ability to repair due to a lack of blood supply. Formerly, tissue engineering was mainly based on collecting chondrocytes from the joint surface, culturing them on resorbable scaffolds such as poly D, L-lactic glycolic acid (PLGA) and then autologous transplantation. In recent times, due to difficulties in collecting chondrocytes, most of the researchers are focused on stem cells for producing these cells. Among the important factors in this approach, is using appropriate scaffolds with good mechanical and biological properties to provide optimal environment for growth and development of stem cells. In this study, we evaluated the potential of fibrin glue, PLGA and alginate scaffolds in providing a suitable environment for growth and chondrogenic differentiation of mesenchymal stem cells (MSCs) in the presence of transforming growth factor-β3.

Materials and Methods:

Fibrin glue, PLGA and alginate scaffolds were prepared and MSCs were isolated from human adipose tissue. Cells were cultured separately on the scaffolds and 2 weeks after differentiation, chondrogenic genes, cell proliferation ability and morphology in each scaffold were evaluated using real time-polymerase chain reaction, MTT chondrogenic assay and histological examination, respectively.

Results:

Proliferation of differentiated adipose tissue derived mesenchymal stem cells (AD-MSCs) to chondrogenic cells in Fibrin glue were significantly higher than in other scaffolds. Also, Fibrin glue caused the highest expression of chondrogenic genes compared to the other scaffolds. Histological examination revealed that the pores of the Fibrin glue scaffolds were filled with cells uniformly distributed.

Conclusion:

According to the results of the study, it can be concluded that natural scaffolds such as fibrin can be used as an appropriate environment for cartilage differentiation.     

Bony defect repair in rabbit using hybrid rapid prototyping polylactic-co-glycolic acid/β-tricalciumphosphate collagen I/apatite scaffold and bone marrow mesenchymal stem cells

Background:

In bone tissue engineering, extracellular matrix exerts critical influence on cellular interaction with porous biomaterial and the apatite playing an important role in the bonding process of biomaterial to bone tissue. The aim of this study was to observe the therapeutic effects of hybrid rapid prototyping (RP) scaffolds comprising polylactic-co-glycolic acid (PLGA), β-tricalciumphosphate (β-TCP), collagen I and apatite (PLGA/β-TCP-collagen I/apatite) on segmental bone defects in conjunction with combination with bone marrow mesenchymal stem cells (BMSCs).

Materials and Methods:

BMSCs were seeded into the hybrid RP scaffolds to repair 15 mm defect in the radius of rabbits. Radiograph, microcomputed tomography and histology were used to evaluate new bone formation.

Results:

Radiographic analysis done from 12 to 36 weeks postoperative period demonstrated that new bone formed at the radial defect site and continues to increase until the medullary cavity is recanalized and remodelling is complete. The bone defect remained unconnected in the original RP scaffolds (PLGA/β-TCP) during the whole study. Histological observations conformed to the radiographic images. In hybrid RP scaffold group, woven bone united the radial defect at 12 weeks and consecutively remodeled into lamellar bone 24 weeks postoperation and finally matured into cortical bone with normal marrow cavity after another 12 weeks. No bone formation but connective tissue has been detected in RP scaffold at the same time.

Conclusion:

Collagen I/apatite sponge composite coating could improve new bone formation in vivo. The hybrid RP scaffold of PLGA/β-TCP skeleton with collagen I/apatite sponge composite coating is a promising candidate for bone tissue engineering.     

Developing biodegradable scaffolds for tissue engineering of the urethra

What’s known on the subject? and What does the study add? The use of tissue engineered buccal mucosa in substitution urethroplasty removes some of the potential drawbacks of harvesting buccal mucosa however it introduces the risk of using donor tissue (allodermis) in its creation. Biocompatible biodegradable non‐woven fabrics created by electrospinning can be used as entirely synthetic matrices for seeding with autologous cells, creating tissues for implantation. This would both remove the donor tissue disease transmission risk and reduce the potential risks of harvesting buccal mucosa. While removing the risks of donor tissue, we showed that we can indeed make a replacement tissue which has similar biomechanical properties to buccal mucosa. We also found that each processing step in the creation of such a tissue is critical, for example the initial sterilisation can have a profound effect on the tissue created.

OBJECTIVE

To develop a synthetic biodegradable alternative to using human allodermis for the production of tissue‐engineered buccal mucosa for substitution urethroplasty, looking specifically at issues of sterilization and cell‐seeding protocols and, comparing the results to native buccal mucosa.

MATERIAL AND METHODS

Three methods of sterilization, peracetic acid (PAA), γ‐irradiation and ethanol, were evaluated for their effects on a biodegradable electrospun scaffold of polylactide‐co‐glycolide (PLGA, 85 : 15), to identify a sterilization method with minimal adverse effects on the scaffolds. Two protocols for seeding oral cells on the scaffold were compared, co‐culture of fibroblasts and keratinocytes on the scaffolds for 14 days, and seeding fibroblasts for 5 days then adding keratinocytes for a further 10 days. Cell viability and proliferation on the scaffolds, scaffold contraction and mechanical properties of the scaffolds with and without cells were examined.

RESULTS

γ‐irradiation and PAA sterilized scaffolds remained sterile for >3 months when incubated in antibiotic‐free culture medium, while ethanol sterilized and unsterilized samples became infected within 2–14 days. All scaffolds showed extensive contraction (up to 50% over 14 days) irrespective of the method of sterilization or the presence of cells. All methods of sterilization, particularly ethanol, reduced the tensile strength of the scaffolds. The addition of cells tended to further reduce mechanical properties but increased elasticity. The cell‐seeding protocol of adding fibroblasts for 5 days followed by keratinocytes for 10 days was the most promising, achieving a mean (sem ) ultimate tensile stress of 1.20 (0.24) × 10⁵ N/m² compared to 3.77 (1.05) × 10⁵ N/m² for native buccal mucosa, and a Young’s modulus of 2.40 (0.25) MPa, compared to 0.73 (0.09) MPa for the native buccal mucosa.

CONCLUSION

This study adds to our understanding of how sterilization and cell seeding affect the physical properties of scaffolds. Both PAA and γ‐irradiation appear to be suitable methods for sterilizing PLGA scaffolds, although both reduce the tensile properties of the scaffolds. Cells grow well on the sterilized scaffolds, and with our current protocol produce constructs which have ≈30% of the mechanical strength and elasticity of the native buccal mucosa. We conclude that sterilized PLGA 85 : 15 is a promising material for producing tissue‐engineered buccal mucosa.     

Tissue-engineered urinary bladder wall using PLGA mesh-collagen hybrid scaffolds: a comparison study of collagen sponge and gel as a scaffold

Purpose: Tissue engineering of the urinary bladder using autologous cells and biodegradable scaffold is a promising method for augmentation. The authors developed 2 hybrid scaffolds by combining poly (DL-lactic-co-glycolic acid; PLGA) mesh for mechanical strength with collagen sponge or gel suitable for cell seeding. The aim of this study was to compare collagen as a scaffold between collagen sponge and gel and to construct a tissue-engineered urinary bladder wall utilizing these hybrid scaffolds.Methods: The PLGA mesh-collagen hybrid scaffolds were prepared by introducing collagen sponge or gel into the PLGA knitted mesh. Urothelial and smooth muscle cells were obtained from porcine urinary bladder wall and were cultured in their respective media. The cells were seeded on these hybrid scaffolds. These constructs were analyzed morphologically and immunohistochemically.Results: The urothelial layer was generated 3 dimensionally by culturing urothelial cells with PLGA mesh and collagen sponge. The smooth muscle layer was constructed by culturing smooth muscle cells with PLGA mesh and collagen gel. And a novel tissue-engineered urinary bladder wall was constructed laminating the urothelial and smooth muscle layers.Conclusions: Ex vivo construction of urinary bladder wall using hybrid scaffolds prepared by combining PLGA mesh with collagen sponge or gel was successful. This tissue-engineered urinary bladder wall allows easy handling and may become a promising tool for bladder augmentation.     

Construction of tissue‐engineered corpus cavernosum with muscle‐derived stem cells and transplantation in vivo

Study Type – Therapy (case series)
Level of Evidence 4 What’s known on the subject? and What does the study add? The tissue‐engineered research of corpus cavernosum has been studied, but an ideal method was not carried out. In the study, muscle‐derived stem cells were used as seeding cells to construct tissue‐engineered corpus cavernosums. The result demonstrated MDSCs could be seeded on three‐dimensional scaffolds of acellular corporal collagen matrices and developed into tissues similar to native corpus cavernosum in vivo.

OBJECTIVE

• ? To investigate the feasibility of tissue‐engineered corpus cavernosum (TECC) with muscle‐derived stem cells (MDSCs) as seed cells and determine the growth potential in vivo.

MATERIALS AND METHODS

• ? Acellular corporal collagen matrices (ACCMs) were obtained from adult rabbit penis by a cell removal procedure. MDSCs were separated and purified using a digestion method and Preplate technique, then seeded on ACCMs at a concentration of 30 × 10⁶ cells/mL to construct TECCs. After 5 days of culture, seeded ACCMs were implanted with albuginea of rabbits. The implants were retrieved at 2, 4 and 6 months after implantation.
• ? Histochemistry, immunohistochemisry and scanning electron microscopy were performed to analyse the morphological characteristics of the TECCs.

RESULTS

• ? The decellularization process successfully extracted all cellular components while preserving the original collagen fibres.
• ? Histological analyses of the explants at all time points in the experimental group had more cells and better arranged growth than the control group. α‐Smooth muscle actin and endothelial nitric oxide synthase‐positive cells were more prevalent in the experimental group.

CONCLUSION

• ? Our study showed that MDSCs can be seeded on three‐dimensional ACCM scaffolds and develop tissues that are similar to native normal corpus cavernosum.

     

Investigation of the long-term patency of a transmural heparinized polycaprolactone and poly(D,L-lactic/glycolic acid) scaffold

Background

The transmural biodegradable polycaprolactone/poly(D,L-lactic/glycolic acid) (PCL/PLGA) scaffold is a promising modality for diffuse coronary atherosclerosis cases that are not suitable for bypass grafting. The purpose of this study was to evaluate the long-term performance of the PCL/PLGA scaffold in vivo in the setting of polymer and heparin degradation.

Materials and methods

After mechanical drilling through the ventricular wall was performed in the whole ventricular wall, two scaffolds were implanted into the ventricular wall. Animals were grouped into the single drilling group (SD group), the blank scaffold group (BS group), and the heparinized scaffold group (HS group) and were allowed to survived for 6 mo. Next, the patency and integrity of the scaffolds were evaluated by echocardiography and 3D-DOCTOR software. Endothelium coverage of the lumen was evaluated by scanning electron microscopy. Neovessels and collagen fiber within the scaffolds were identified by histologic staining. Metabolite production of prostacyclin (PGI₂) and thromboxane A₂ (TXA₂) in the plasma was measured by an enzyme-linked immunosorbent assay. The expression levels of PGI₂ synthase and cyclooxygenase 2 (COX-2) involved in PGI₂ production and COX-1 involved in TXA₂ production were measured by Western blot analysis.

Results

The heparinized scaffolds were patent for up to 6 mo and the lumen was covered with confluent endothelial cells. Histologic staining revealed collagen fiber remodeling and reconstruction of the neovascular network immediately surrounding the lumen. The expression of PGI₂ synthase and COX-2 in the HS group was significantly higher compared with the SD and BS groups (P < 0.01). The expression of COX-1 was similar in the three groups (P > 0.05). Consistent with synthetase expression, a PGI₂ metabolite (6-keto-PGF1a) also showed a significant increase in the HS group relative to the SD and BS groups (P = 0.021 and P = 0.015, respectively). Concomitantly, as a PGI₂ antagonist, the TXA₂ metabolite (TXB₂) did not exhibit a significant difference among the three groups (P = 0.17).

Conclusions

Despite polymer and heparin degradation, the scaffold could continuously maintain the structural integrity and lumen patency for up to 6 mo by reinforcement of host collagen fiber and the balance of PGI₂/TXA₂.     

Improved in vitro cultivation of endothelial progenitor cells as basis for dermal substitutes with enhanced angiogenic capabilities

Purpose  

Endothelial progenitor cells (EPCs) are a promising cell source for vascular tissue engineering approaches in surgery. Diverse biomaterials have been used as matrices for EPC cultivation. In this in vitro study, fibrin in combination with growth factors was examined as an optimized culturing scaffold for EPCs.     

Biocompatibility of Poly-ε-caprolactone-hydroxyapatite composite on mouse bone marrow-derived osteoblasts and endothelial cells

Background  

Tissue-engineered bone may be developed by seeding the cells capable of both osteogenesis and vascularization on biocompatible composite scaffolds. The current study investigated the performance of mice bone marrow-derived osteogenic cells and endothelial cells as seeded on hydroxyapatite (HA) and poly-ε-caprolactone (PCL) composite scaffolds.     

Proliferation of ASC-derived endothelial cells in a 3D electrospun mesh: Impact of bone-biomimetic nanocomposite and co-culture with ASC-derived osteoblasts

Background

Fractures with a critical size bone defect are associated with high rates of delayed- and non-union. The treatment of such complications remains a serious issue in orthopaedic surgery. Adipose derived stem cells (ASCs) combined with biomimetic materials can potentially be used to increase fracture healing. Nevertheless, a number of requirements have to be fulfilled; in particular, the insufficient vascularisation of the bone constructs. Here, the objectives were to study the impact of ASC-derived osteoblasts on ASC-derived endothelial cells in a 3D co-culture and the effect of 40 wt% of amorphous calcium phosphate nanoparticles on the proliferation and differentiation of ASC-derived endothelial cells when present in PLGA.

Materials and methods

Five primary ASC lines were differentiated towards osteoblasts (OBs) and endothelial cells (ECs) and two of them were chosen based on quantitative PCR results. Either a mono-culture of ASC-derived EC or a co-culture of ASC-derived EC with ASC-derived OB (1:1) was seeded on an electrospun nanocomposite of poly-(lactic-co-glycolic acid) and amorphous calcium phosphate nanoparticles (PLGA/a-CaP; reference: PLGA). The proliferation behaviour was determined histomorphometrically in different zones and the expression of von Willebrand Factor (vWF) was quantified.

Results

Independently of the fat source (biologic variability), ASC-derived osteoblasts decelerated the proliferation behaviour of ASC-derived endothelial cells in the co-culture compared to the mono-culture. However, expression of vWF was clearly stronger in the co-culture, indicating further differentiation of the ASC-derived EC into the EC lineage. Moreover, the presence of a-CaP nanoparticles in the scaffold slowed the proliferation behaviour of the co-culture cells, too, going along with a further differentiation of the ASC-derived OB, when compared to pure PLGA scaffolds.

Conclusions

This study revealed significant findings for bone tissue-engineering. Co-cultures of ASC-derived EC and ASC-derived OB stimulate each other's further differentiation. A nanocomposite with a-CaP nanoparticles offers higher mechanical stability, bioactivity and osteoconductivity compared to mere PLGA and can easily be seeded with pre-differentiated EC and OB.     

An ovine in vitro model for chondrocyte-based scaffold-assisted cartilage grafts

Background

Scaffold-assisted autologous chondrocyte implantation is an effective clinical procedure for cartilage repair. From the regulatory point of view, the ovine model is one of the suggested large animal models for pre-clinical studies. The aim of our study was to evaluate the in vitro re-differentiation capacity of expanded ovine chondrocytes in biomechanically characterized polyglycolic acid (PGA)/fibrin biomaterials for scaffold-assisted cartilage repair.

Methods

Ovine chondrocytes harvested from adult articular cartilage were expanded in monolayer and re-assembled three-dimensionally in PGA-fibrin scaffolds. De- and re-differentiation of ovine chondrocytes in PGA-fibrin scaffolds was assessed by histological and immuno-histochemical staining as well as by real-time gene expression analysis of typical cartilage marker molecules and the matrix-remodelling enzymes matrix metalloproteinases (MMP) -1, -2 and ?13 as well as their inhibitors. PGA scaffolds characteristics including degradation and stiffness were analysed by electron microscopy and biomechanical testing.

Results

Histological, immuno-histochemical and gene expression analysis showed that dedifferentiated chondrocytes re-differentiate in PGA-fibrin scaffolds and form a cartilaginous matrix. Re-differentiation was accompanied by the induction of type II collagen and aggrecan, while MMP expression decreased in prolonged tissue culture. Electron microscopy and biomechanical tests revealed that the non-woven PGA scaffold shows a textile structure with high tensile strength of 3.6 N/mm² and a stiffness of up to 0.44 N/mm², when combined with gel-like fibrin.

Conclusion

These data suggest that PGA-fibrin is suited as a mechanically stable support structure for scaffold-assisted chondrocyte grafts, initiating chondrogenic re-differentiation of expanded chondrocytes.     

Induction of porcine‐specific regulatory T cells with high specificity and expression of IL‐10 and TGF‐β1 using baboon‐derived tolerogenic dendritic cells

Background

Regulatory T cells (Treg) play an important role in maintenance of homeostasis in vivo. Treg application to alleviate allo‐organ rejection is being studied extensively. However, natural Treg (nTreg) expansion in vitro is laborious and expensive. Antigen‐specific Treg are more effective and require lower cell numbers than use of nTreg for immune control. The baboon, as a non‐human primate experimental animal model, is widely used in xenotransplantation research. An effective method to generate baboon xeno‐specific Treg would benefit research on immune tolerance in xenotransplantation using this model system.

Method

Baboon tolerogenic dendritic cells (tolDC) were generated in 3 days from monocytes isolated from baboon peripheral blood mononuclear cells in medium supplemented with anti‐inflammatory cytokines. After loading with porcine‐specific (PS) in vitro‐transcribed RNA (ivtRNA), tolDC were used to induce CD4⁺ T cells to become porcine‐specific Treg (PSTreg) in cocultures supplemented with IL‐2 and rapamycin for 10 days. Anti‐inflammatory and inflammatory cytokine expression was evaluated at the mRNA and protein levels in both baboon tolDC and PSTreg. Functional assays, suppression of activation markers on porcine‐specific effector T cells (PSTeff) and inhibition of PSTeff proliferation, were used to test PSTreg specificity.

Results

TolDC generated with this method exhibited a tolerogenic phenotype, expressed CCR7 and produced high levels of IL‐10 and TGF‐β1, whereas IL‐12p40 and IFN‐γ were not expressed. PSTreg were successfully generated in cocultures of CD4⁺ T cells and PS ivtRNA‐loaded tolDC. They exhibited a CD3⁺ CD4⁺ CD25⁺ CD127^low/? CD45RA^low Foxp3⁺ phenotype and were characterized by high expression of IL‐10 and TGF‐β1 mRNA and protein. They showed upregulated expression of EBI3 and GARP mRNA. PSTreg exhibited highly suppressive effects toward PSTeff, secreting high amounts of IL‐10 and TGF‐β1 cytokine upon interaction with PSTeff and suppressing IFN‐γ expression on PSTeff.

Conclusion

In this study, a fast 3‐day method to generate baboon‐derived tolDC is provided that allows subsequent induction of PSTreg displaying high porcine‐antigen specificity and expression of IL‐10 and TGF‐β1. Porcine‐specific baboon Treg can be used in porcine solid organ or cell xenotransplantation studies through adoptive cell transfer into host baboons.     

An in vitro model of biomaterial-augmented microfracture including chondrocyte–progenitor cell interaction

Background  

Biomaterials, acting as scaffolds for cell migration and differentiation, may be used to improve outcomes after microfracture. Three mechanisms determine the success of such procedures and are tested herein: the general capacity of adult femoral mesenchymal progenitor cells (MPC) to differentiate into cartilage, their capacity to do so in a biomaterial, and finally potential interactions between MPC and autologous chondrocytes.     

Stem Cells, Mature Adipocytes, and Extracellular Scaffold: What Does Each Contribute to Fat Graft Survival?

Background  

Soft tissue engineering offers new perspectives for improving fat graft survival, for which the appropriate association of cells and scaffold seems essential. This study aimed to analyze the survival of free-cell grafts compared with adipose-derived stem cells (ASCs) seeded on collagen scaffolds.     

Mesh fixation with fibrin glue (Tissucol/Tisseel®) in hernia repair dependent on the mesh structure—is there an optimum fibrin–mesh combination?—Investigations on a biomechanical model

Background  

Because of its hemostatic and adhesive properties, fibrin glue has been used in many areas of surgical treatment in recent years. One example is hernia repair, where fibrin gluing has become increasingly established as an alternative method for mesh fixation. Clinically, fixation with fibrin glue shows a reduced postoperative complication rate compared to other fixation methods (staples, sutures), particularly with regard to pain.     

A novel strategy of spine defect repair with a degradable bioactive scaffold preloaded with adipose-derived stromal cells

Background contextAlthough the use of mesenchymal stem cells (MSC) with scaffolds for bone repair has been considered an effective method, the interactions between implanted materials and bone tissues have not been fully elucidated. At some specific sites, such as the vertebral body (VB) of the spine, the process of bone repair with implanted biomaterials is rarely reported. Recently, adipose tissue was found to be an alternative source of MSC besides bone marrow. However, the strategy of using adipose-derived stromal (ADS) cells with bioactive scaffold for the repair of spinal bone defects has seldom been studied.PurposeTo use a sintered poly(lactide-co-glycolide) acid (PLGA) microspheres scaffold seeded with induced rat ADS cells to repair a bone defect of the VB in a rat model.Study designBasic science and laboratory study.MethodsA sintered porous microspheres scaffold was manufactured by PLGA. ADS cells were isolated from Fischer 344 rats and then induced by osteogenic medium with growth and differentiation factor 5 (GDF5) in vitro. Before implantation, cells were cultured with inductive media for 2 weeks as a monolayer situation and 1 more week on a PLGA scaffold as a three-dimensional structure. These assembled bioactive scaffolds then were implanted in lumbar VB bone defects in Fischer 344 rats. The ex vivo differentiation of the cells was confirmed by von Kossa staining and real-time polymerase chain reaction. The performance of cells on the scaffold was detected by scanning electron microscopy and (3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium) assay. In vivo bone formation was quantitatively measured by computed tomography study. And the effect of tissue repair was also evaluated by histological studies.ResultsProliferation and differentiation of cells were confirmed before in vivo implantation. Quantification of bone formation in vivo through serial three-dimensional computed tomography images revealed that the VB implanted with GDF5-induced cells demonstrated more bone formation than the control groups. Besides the bone formation period that occurred between 2 and 4 weeks in all groups, a second bone formation period was found to occur only in the groups that received cells with previous induction in vitro. This second period of significant bone formation happened simultaneously with collapsing of the scaffolds. It was then demonstrated histologically that vascularization early in the process and cooperation between host bone and implanted cells accompanied by collapse of the scaffold may be the factors that influence bone formation. This study not only provides a therapeutic strategy of using biomaterial for bone repair in the spine, but also may lead to a technological method for studying the relationship between implanted stem cells and host tissue.ConclusionsAdipose-derived stromal cells maintained in culture on a scaffold and treated with osteogenic induction with growth factor ex vivo could be used to enhance bone repair in vivo.     

Using safe,affordable and accessible non‐steroidal anti‐inflammatory drugs to reduce the number of HIV target cells in the blood and at the female genital tract

Introduction

At its basic level, HIV infection requires a replication‐competent virus and a susceptible target cell. Elevated levels of vaginal inflammation has been associated with the increased risk of HIV infection as it brings highly activated HIV target cells (CCR5+CD4+ T cells; CCR5+CD4+CD161+ Th17 T cells) to the female genital tract (FGT) where they interact with HIV. Decreased HIV risk has been associated with a phenotype of decreased immune activation, called immune quiescence, described among Kenyan female sex workers who were intensely exposed to HIV yet remain uninfected. Current prevention approaches focus on limiting viral access. We took the novel HIV prevention approach of trying to limit the number of HIV target cells in the genital tract by reducing inflammation using safe, affordable and globally accessible anti‐inflammatory drugs.

Methods

We hypothesized that the daily administration of low doses of acetylsalicylic acid (ASA 81 mg) or hydroxychloroquine (HCQ 200 mg) would reduce inflammation thereby decreasing HIV target cells at the FGT. Low‐risk HIV seronegative women from Nairobi, Kenya were randomized for six weeks therapy of ASA (n = 37) or HCQ (n = 39) and tested to determine the impact on their systemic and mucosal immune environment.

Results

The results showed that HCQ use was associated with a significant reduction in the proportion of systemic T cells that were CCR5+CD4+ (p = 0.01) and Th17 (p = 0.01). In the ASA arm, there was a 35% and 28% decrease in the proportion of genital T cells that were CD4+CCR5+ (p = 0.017) and Th17 (p = 0.04) respectively. Proteomic analyses of the cervical lavage showed ASA use was associated with significantly reduced amount of proteins involved in the inflammatory response and cell recruitment at the mucosa, although none of the individual proteins passed multiple comparison correction. These changes were more apparent in women with Lactobacillus dominant microbiomes.

Conclusion

Together, these data indicate that taking low‐dose ASA daily was associated with significant reduction in HIV target cells at the FGT. This study provides proof‐of‐concept for a novel HIV‐prevention approach that reducing inflammation using safe, affordable and globally accessible non‐steroidal anti‐inflammatory agents is associated with significant reduction in the proportion of HIV‐target cells at the FGT.

     

Dermatan sulphate in methoxy polyethylene glycol-polylactide-co-glycolic acid scaffolds upregulates fibronectin gene expression but has no effect on in vivo osteochondral repair

Purpose

The purpose of the study was to investigate the effect of dermatan sulphate (DS) addition to biodegradable methoxy polyethylene glycol (MPEG) substituted polylactide-co-glycolic acid (PLGA) scaffolds for cartilage repair in vitro and in vivo.

Methods

Human chondrocytes from eight patients undergoing anterior cruciate ligament reconstruction were isolated and cultured in 5% oxygen on MPEG-PLGA scaffolds ± DS for one, three, seven and 14 days. Analyses were performed using quantitative gene expression analysis for chondrogenic and cell attachment markers. An osteochondral drill hole defect was created in the intertrochlear groove of the distal femur in 20 New Zealand white rabbits (defects n = 20). When bleeding was observed, the defects were treated with MPEG-PLGA scaffolds ± DS. Twelve weeks after surgery the rabbits were sacrificed and the defects were analysed using histological grading with O’Driscoll scoring.

Results

DS addition to MPEG-PLGA scaffolds resulted in a significant upregulation of fibronectin gene expression on day 1. No differences were observed in chondrogenic gene expression. There were no differences between the two groups in histological grading (+DS 10.3 and −DS 9.6).

Conclusions

Upregulation of fibronectin in vitro indicating early cell-scaffold interaction and attachment did not result in improved cartilage repair in an osteochondral defect model in rabbits.     

血管化组织工程肝小块构建的研究

目的 利用组织工程方法和原理初步构建血管化肝小块组织。方法 肝细胞和肝窦内皮细胞取自小鼠肝脏。采用内管网高分子聚酯类聚合物（PLGA）材料作为支架。肝窦内皮细胞接种在内管网PLGA支架管道的内壁使之在体外预内皮化。肝细胞与纤维蛋白原混合制成肝细胞／纤维蛋白原混合液，接种在喷洒有凝血酶的预内皮化的内管网支架上。构建的复合物分别植于小鼠肠系膜部位（A组）和肝组织表面（B组）．2周后将支架取出观察，比较不同部位的植入效果。结果 支架体外预血管化后，其管道内可见内皮细胞均匀贴壁；体内植入后内皮细胞优势生长；A组小鼠肠系膜间支架中有血管长入，但未见有肝细胞留存；B组可见支架内有少量肝细胞团，并有血管长入。结论 简易PLGA内管网多孔支架可以用于肝组织小块的构建．而肝组织表面更适合组织工程肝小块的体内植入。     

Use of Fibrin Sealants in Cardiovascular Surgery: A Systematic Review

Background

Fibrin sealants are used for hemostasis and tissue adherence.

Aim of Study

This systematic review summarizes published clinical data for fibrin sealant use in cardiovascular surgery.

Methods

A literature search for the following terms was conducted using PubMed and EMBASE: (TISSEEL or Tissucol or Beriplast P or Evicel or Quixil or Crosseal or Reliseal or Fibringluraas or Bolheal or Tachosil or Vivostat or Vitagel or Artiss or “fibrin glue” or “fibrin sealant” or “fibrin tissue adhesive”) and (cardiac or cardiovascular or vascular or heart or coronary or surgery). Case reports and series were excluded; although reports of controlled trials were preferred, uncontrolled trial data were also considered.

Results

Clinical trials and chart review analyses of fibrin sealants were identified and summarized. Although clinical trial data were available for other agents, the majority of published studies examined TISSEEL. Overall, TISSEEL and other fibrin sealants showed improvements over standard of care or control groups for a variety of predefined endpoints. Safety findings are also summarized.

Conclusions

Data from these studies showed that fibrin sealants were well tolerated and provided effective hemostasis in a range of cardiac and aortic surgeries. doi: 10.1111/jocs.12099 (J Card Surg 2013;28:238–247)     

Adhesion and proliferation of human osteoblast-like cells on different biodegradable implant materials used for graft fixation in ACL-reconstruction

Introduction

This study investigates the adhesion and proliferation behaviour of human osteoblast-like cells over time when incubated on surfaces of biodegradable screws and pins used for graft fixation in ACL reconstruction.

Materials and methods

2?mm-sized-wedges of four bioresorbable implants [1. poly-l-lactide acid (PLLA) screw, 2. PLLA/β-tricalciumphosphate (PLLA/TCP) (70?%/30?%) screw, 3. poly-l-lactide-co-glycolic acid/β-tricalciumphosphate (PLGA/TCP) (70?%/30?%) screw and 4. PLLA pin] were incubated with human osteoblast-like cells. All probes were evaluated after 3,7,14 and 21?days by cell number count, determination of cell proliferation, observation of cell adhesion of human osteoblast-like cells under an environmental scanning electron microscope (ESEM), and by a live-dead assay.

Results

Cell numbers were lower at all stages in both PLLA groups compared to the composite materials (PLLA/TCP and PLGA/TCP). A significant difference in cell proliferation was found after 21?days. The cells on both composite screws (PLLA/TCP and PLGA/TCP) maintained more contact points with the screw surface compared to the cells on PLLA screws under ESEM. No cytotoxicity could be observed in the live-dead assay.

Discussion

Mainly, β-TCP as part of a composite implant seems to offer good ultrastructural properties for cell adhesion according to our in vitro study. Cell numbers seem to be influenced by the degradation behaviour with higher cell numbers in the composite groups.