Biodegradable honeycomb collagen scaffold for dermal tissue engineering

Tissue engineering requires a mechanically stable, biocompatible, and biodegradable scaffold that permits cell adherence and proliferation, allows preservation of cell-specific properties, and suitable for surgical implantations. In this study, honeycomb collagen sheet was used for three-dimensional (3D) cultures of human skin fibroblasts and characterized as an effective and suitable scaffold for dermal tissue engineering. About 1-mm-thick honeycomb collagen sheets, prepared from bovine dermal atelocollagen, cross-linked by UV-irradiation, and sterilized by heat, were placed on the proliferating fibroblasts on day 3 of the culture. The cells attached quickly to the collagen scaffold, proliferated inside the honeycomb pores, and formed a structure similar to dermis within 60 days. On day 60, total cellular DNA content of the 3D cultures was 12-fold higher when compared with the 2D control cultures without the scaffold. Measurement of procollagen type I in the media demonstrated a 20-fold increase. Scanning electron microscopy of the 3D cultures showed a well-formed structure similar to dermis and biodegradation of the honeycomb collagen scaffold. Our study proved that honeycomb collagen sheet is a mechanically stable, biocompatible and biodegradable scaffold for dermal tissue engineering, and also potentially useful for other cell-based therapies and tissue engineering applications.     

A three-dimensional nanofibrous scaffold for cartilage tissue engineering using human mesenchymal stem cells

The utilization of adult stem cells in tissue engineering is a promising solution to the problem of tissue or organ shortage. Adult bone marrow derived mesenchymal stem cells (MSCs) are undifferentiated, multipotential cells which are capable of giving rise to chondrocytes when maintained in a three-dimensional culture and treated with members of the transforming growth factor-beta (TGF-beta) family of growth factors. In this study, we fabricated a nanofibrous scaffold (NFS) made of a synthetic biodegradable polymer, poly(-caprolactone) (PCL), and examined its ability to support in vitro chondrogenesis of MSCs. The electrospun PCL porous scaffold was constructed of uniform, randomly oriented nanofibers with a diameter of 700 nm, and structural integrity of this scaffold was maintained over a 21-day culture period. MSCs cultured in NFSs in the presence of TGF-beta1 differentiated to a chondrocytic phenotype, as evidenced by chondrocyte-specific gene expression and synthesis of cartilage-associated extracellular matrix (ECM) proteins. The level of chondrogenesis observed in MSCs seeded within NFSs was comparable to that observed for MSCs maintained as cell aggregates or pellets, a widely used culture protocol for studying chondrogenesis of MSCs in vitro. Due to the physical nature and improved mechanical properties of NFSs, particularly in comparison to cell pellets, the findings reported here suggest that the PCL NFS is a practical carrier for MSC transplantation, and represents a candidate scaffold for cell-based tissue engineering approaches to cartilage repair.     

In vitro cartilage tissue engineering using adipose-derived extracellular matrix scaffolds seeded with adipose-derived stem cells

Extracellular matrix (ECM) secreted from the resident cell of tissue is an ideal biomaterial evolved by nature. Cartilage is also built from well-organized ECM components in a gel-like structure with a high collagen and proteoglycan content. Here, we explored cartilage tissue engineering using ECM scaffolds seeded with stem cells. Both scaffolds and stem cells were isolated from human adipose tissue, which is abundant and easily harvested in the human body. The human ECM scaffolds contained various endogenous bioactive factors, including transforming growth factor-beta1 (TGF-β1, 8782±4989?pg/g, dry ECM), insulin growth factor-1 (13319±1388?pg/g, dry ECM), basic fibroblast growth factor (82373±9572?pg/g, dry ECM), and vascular endothelial growth factor (25647±2749?pg/g, dry ECM). A composite of ECM and stem cells was prepared and cultured in chondrogenic medium (with 10?ng/mL TGF-β1 or not) for 45 days. The volumes and weights of the composites increased during culture and the surface gradually became smooth. Cell viability remained high throughout the 45 days of in vitro culture. Composites showed the formation of cartilage-like tissue with the synthesis of cartilage-specific proteins such as collagen and glycosaminoglycan. Important chondrogenic markers were expressed including Sox-9, aggrecan, and collagen type II and XI. These results demonstrate that a cell/ECM composite containing endogenous bioactive factors could provide biochemical cues for the promotion of cartilage formation.     

PHB/PHBHHx scaffolds and human adipose-derived stem cells for cartilage tissue engineering

The goal of this study was to investigate the potential of polyhydroxybutyrate (PHB)/poly(hydroxybutyrate-co-hydroxyhexanoate) (PHBHHx) (PHB/PHBHHx) to produce neocartilage upon seeding with differentiated human adipose-derived stem cells (hASCs). hASCs were grown on a three-dimensional PHB/PHBHHx scaffold in vitro with or without chondrogenic media for 14 days. Scanning electron microscopy showed that differentiated cells produced abundant extracellular matrices with increasing culture time. No cytotoxicity was observed by the live/dead cell viability assay. GAG and total collagen content in the differentiated cells increased significantly with in vitro culture time. After 14 days of in vitro culture, the differentiated cells grown on the (PHB/PHBHHx) scaffold (differentiated cells/(PHB/PHBHHx)) were implanted into the subcutaneous layer nude mice for 12 or 24 weeks, non-differentiated cells/(PHB/PHBHHx) were implanted as the control group. The differentiated cells/(PHB/PHBHHx) implants formed cartilage-like tissue after 24 weeks of implantation, and stained positive for collagen type II, safranin O, and toluidine blue. In addition, typical cartilage lacuna was observed, and there were no remnants of PHB/PHBHHx. Collagen type II was detected by Western blot at 12 and 24 weeks of implantation. In the control group, no cartilage formation was observed. This study demonstrated that PHB/PHBHHx is a suitable material for cartilage tissue engineering.     

Combining decellularized human adipose tissue extracellular matrix and adipose-derived stem cells for adipose tissue engineering

Repair of soft tissue defects resulting from lumpectomy or mastectomy has become an important rehabilitation process for breast cancer patients. This study aimed to provide an adipose tissue engineering platform for soft tissue defect repair by combining decellularized human adipose tissue extracellular matrix (hDAM) and human adipose-derived stem cells (hASCs). To derive hDAM incised human adipose tissues underwent a decellularization process. Effective cell removal and lipid removal were proved by immunohistochemical analysis and DNA quantification. Scanning electron microscopic examination showed a three-dimensional nanofibrous architecture in hDAM. The hDAM included collagen, sulfated glycosaminoglycan, and vascular endothelial growth factor, but lacked major histocompatibility complex antigen I. hASC viability and proliferation on hDAM were proven in vitro. hDAM implanted subcutaneously in Fischer rats did not cause an immunogenic response, and it underwent remodeling, as indicated by host cell infiltration, neovascularization, and adipose tissue formation. Fresh fat grafts (Coleman technique) and engineered fat grafts (hDAM combined with hASCs) were implanted subcutaneously in nude rats. The implanted engineered fat grafts maintained their volume for 8 weeks, and the hASCs contributed to adipose tissue formation. In summary, the combination of hDAM and hASCs provides not only a clinically translatable platform for adipose tissue engineering, but also a vehicle for elucidating fat grafting mechanisms.     

脂肪干细胞在骨组织工程中的研究进展

各种原因导致的骨损伤甚至骨缺损会给患者带来较大的经济及社会负担,而骨组织工程研究能为治疗骨损伤提供新的方向。脂肪干细胞因其来源广泛、易于获取等特性在骨组织工程中发挥着重要作用,且脂肪干细胞在生长因子、机械刺激、各种信号通路的适宜刺激下能进行自我增殖并成骨分化,形成骨组织以治疗骨损伤及骨缺损,改善骨损伤带来的一系列症状。     

脂肪干细胞在软骨组织工程中的应用

软骨是最早应用组织工程技术成功构建的组织之一,但由于缺乏合适的软骨构建种子细胞,因此其发展相对落后。随着干细胞研究的兴起,脂肪干细胞（ASC）因其具有分布广泛、可利用细胞量大、取材容易等优点,为ASC作为种子细胞应用于组织工程研究提供了可能;但是ASC构建软骨组织的效果却不如骨髓间充质干细胞（BMSC）理想。因此ASC在软骨组织工程中的应用仍面临着诸多问题与挑战,其中最核心的问题是如何提高ASC成软骨的效率。为此从如何纯化脂肪来源细胞、尽可能保持其中干细胞的生物学特性并优化软骨诱导方案3个方面予以综述,为提高ASC成软骨的效率提供参考。     

自体脂肪干细胞复合胶原海绵多孔支架构建大鼠乳腺脂肪组织的初步研究

目的 探讨自体脂肪干细胞复合胶原海绵多孔支架构建大鼠乳腺脂肪组织的可行性.方法 采用胶原酶消化、离心方法分离并培养6只雌性SD大鼠的脂肪干细胞.对脂肪干细胞进行成骨、成脂诱导及鉴定.将自体脂肪干细胞复合Ⅰ型胶原海绵多孔支架进行体外培养.将自体脂肪干细胞复合Ⅰ型胶原海绵多孔支架移植到大鼠右上侧乳腺(实验组),将Ⅰ型胶原海绵多孔支架移植到大鼠左上侧乳腺(对照组),共移植6例.12周后观测有无新生脂肪形成;测量新生脂肪组织湿质量;组织切片行HE及油红0染色.结果 SD大鼠脂肪干细胞增殖能力强;具有成骨及成脂分化能力;体外培养2周,胶原支架内可见ASC生长.实验组可见乳腺与胸肌之间有脂肪样新生组织形成,平均湿质量为(121±9) mg.对照组见乳腺与胸肌之间有胶原海绵样组织形成,平均湿质量为(77±6) mg,两组间湿质量存在统计学差异,P＜0.05.HE及油红O染色证实,实验组新生组织主要为成熟脂肪组织;而对照组主要为胶原纤维.结论 自体脂肪干细胞复合Ⅰ型胶原海绵多孔支架可在大鼠乳腺区域形成脂肪组织.     

Adipose tissue engineering by human adipose-derived stromal cells

Tissue engineering has emerged as a promising alternative approach to current clinical treatments for restoration of soft tissue defects. The purpose of this study was to investigate adipose tissue formation in vitro and in vivo by using human adipose-derived stromal cells (ADSCs) utilizing a gelatin sponge (Gelform) as a scaffold. Adipogenic potentials of human ADSCs were demonstrated by Oil-O-red staining and cellular morphology. After seeding human ADSCs in a density of 3 x 10(6) cells/ml on three-dimensional gelatin sponges, tissue-engineered constructs were exposed to adipogenic differentiation medium for in vitro studies and implanted in the backs of severe combined immunodeficient (SCID) mice for in vivo adipose regeneration. Adipogenesis of ADSC-seeded gelatin sponges was confirmed by Oil-O-red staining after 4 weeks of in vitro incubation. The optical density of the elution from Oil-O-red staining of adipogenic constructs is significantly higher than that of the control group (p < 0.05, n = 4). With short-term in vitro differentiation, adipogenic constructs turned into fat tissue 4 weeks after in vivo implantation, confirmed by biochemical and immunohistochemical examination. No adipogenic-morphological change or fat formation was observed in in vitro or in vivo studies when ADSCs were exposed to a control medium without adipogenic stimulation. These results indicate that engineered adipose tissue can be achieved using human ADSCs and biocompatible and degradable gelatin sponges.     

脂肪干细胞在骨软骨组织工程中的研究进展

近年来,随着医学相关学科的迅猛发展,组织工程技术已经取得了很大的成就,但种子细胞一直是困扰人们的焦点问题.脂肪干细胞(ADSCs)体外扩增迅速,稳定性好,无免疫排斥反应,具有多向分化潜能,可以向脂肪细胞、成骨细胞、成软骨细胞、内皮细胞、肌细胞和神经细胞等不同胚层来源的细胞分化,并且脂肪组织具有取材方便、对人体创伤小、可大量获得等优点,因而ADSCs有望成为一种理想的组织工程种子细胞.旨在介绍ADSCs在骨软骨组织工程中的研究进展.     

Adipose tissue engineering with naturally derived scaffolds and adipose-derived stem cells

A tissue-engineered adipose substitute would have numerous applications in plastic and reconstructive surgery. This work involves the characterization of the in vitro cellular response of primary human adipose-derived stem cells (ASC) to three dimensional, naturally derived scaffolds. To establish a more thorough understanding of the influence of the scaffold environment on ASC, we have designed several different soft tissue scaffolds composed of decellularized human placenta and crosslinked hyaluronan (XLHA). The cellular organization within the scaffolds was characterized using confocal microscopy. Adipogenic differentiation was induced and the ASC response was characterized in terms of glycerol-3-phosphate dehydrogenase (GPDH) activity and intracellular lipid accumulation. The results indicate that the scaffold environment impacts the ASC response and that the adipogenic differentiation of the ASC was augmented in the non-adhesive XLHA gels.     

Development of silk-based scaffolds for tissue engineering of bone from human adipose-derived stem cells

Silk fibroin is a potent alternative to other biodegradable biopolymers for bone tissue engineering (TE), because of its tunable architecture and mechanical properties, and its demonstrated ability to support bone formation both in vitro and in vivo. In this study, we investigated a range of silk scaffolds for bone TE using human adipose-derived stem cells (hASCs), an attractive cell source for engineering autologous bone grafts. Our goal was to understand the effects of scaffold architecture and biomechanics and use this information to optimize silk scaffolds for bone TE applications. Silk scaffolds were fabricated using different solvents (aqueous vs. hexafluoro-2-propanol (HFIP)), pore sizes (250-500 μm vs. 500-1000 μm) and structures (lamellar vs. spherical pores). Four types of silk scaffolds combining the properties of interest were systematically compared with respect to bone tissue outcomes, with decellularized trabecular bone (DCB) included as a "gold standard". The scaffolds were seeded with hASCs and cultured for 7 weeks in osteogenic medium. Bone formation was evaluated by cell proliferation and differentiation, matrix production, calcification and mechanical properties. We observed that 400-600 μm porous HFIP-derived silk fibroin scaffold demonstrated the best bone tissue formation outcomes, as evidenced by increased bone protein production (osteopontin, collagen type I, bone sialoprotein), enhanced calcium deposition and total bone volume. On a direct comparison basis, alkaline phosphatase activity (AP) at week 2 and new calcium deposition at week 7 were comparable to the cells cultured in DCB. Yet, among the aqueous-based structures, the lamellar architecture induced increased AP activity and demonstrated higher equilibrium modulus than the spherical-pore scaffolds. Based on the collected data, we propose a conceptual model describing the effects of silk scaffold design on bone tissue formation.     

膨体聚四氟乙烯与人脂肪干细胞的体外生物相容性

背景：膨体聚四氟乙烯多孔高分子聚合材料是临床常用的植入假体,具有良好的生物相容性,不易变形、变质,不产生炎症吸收反应,可允许细胞游走和组织向内生长。 目的：观察人脂肪干细胞与膨体聚四氟乙烯材料的生物相容性。 方法：将第4代人脂肪干细胞与膨体聚四氟乙烯体外复合培养,采用倒置相差显微镜观察细胞在支架上黏附、生长及增殖情况,计算细胞黏附率,MTT比色法检测细胞增殖率。 结果与结论：刚接种的细胞呈圆形透亮,在支架材料表面分布均匀,细胞活性佳,3 h后大量细胞贴壁,24 h后可见少量呈短梭形的脂肪干细胞贴壁,3 d首次换液,细胞清晰可见,低密度生长时呈短梭形或多角形,分布均匀,种植7 d后细胞数量明显增加,极少细胞从支架上掉落,细胞黏附率平均达95.7%,并且细胞仍保持正常的分裂增殖速度。说明膨体聚四氟乙烯材料具有良好的细胞相容性,可作为脂肪组织工程的种子。中国组织工程研究杂志出版内容重点：生物材料;骨生物材料; 口腔生物材料; 纳米材料; 缓释材料; 材料相容性;组织工程全文链接：     

脂肪干细胞三维生长骨组织工程复合体的构建

背景：组织工程支架是模仿细胞赖以生长代谢的细胞外基质而构建的支架和环境,其选择、制备以及种子细胞的选择是骨组织工程领域中的一项十分重要的课题。 目的：利用几丁质凝胶/异种骨构建脂肪干细胞三维生长环境,并对其相容性进行研究。 方法：从出生8 d新西兰大白兔腹股沟获取脂肪组织,提取脂肪干细胞。脂肪干细胞经过体外成骨诱导分化后,种植于几丁质凝胶/异种骨,构建新型骨组织工程复合体,并将其设为细胞/几丁质凝胶/异种骨组;将脂肪干细胞直接种植于异种骨,构成脂肪干细胞/异种骨复合体作为细胞/异种骨组,单独异种骨为空白组。体外诱导2周后进行电镜扫描,观察细胞与支架的复合情况。 结果与结论：镜扫描观察显示几丁质凝胶充分渗透于支架的空隙内,形成一个细胞的三维生长环境,使原本只能在材料上贴壁生长的脂肪干细胞能够在三维的环境中生长,为细胞外基质的再生提供足够的空间。几丁质凝胶/异种骨悬浮诱导后的脂肪干细胞,承载了更多的细胞,减少了细胞在载体中的流失,是一种较好的骨组织工程载体。 中国组织工程研究杂志出版内容重点：组织构建;骨细胞;软骨细胞;细胞培养;成纤维细胞;血管内皮细胞;骨质疏松;组织工程全文链接：     

Bone tissue engineering using bone marrow stromal cells and an injectable sodium alginate/gelatin scaffold

To investigate the potential application of bone marrow stromal cells (BMSCs) and an injectable sodium alginate/gelatin scaffold for bone tissue engineering (BTE). The phenotype of osteogenic BMSCs was examined by mineralized nodules formation and type I collagen expression. Cell proliferation was evaluated by MTT assay. The biocompatibility of scaffold and osteogenic cells were examined by hematoxylin and eosin (H&E) staining. Ectopic bone formation as well as closure of rabbit calvarial critical-sized defects following scaffold-cell implantation were analyzed by histological examination and computed tomography (CT) scanning. Spindle-shaped osteogenic cells of high purity were derived from BMSCs. The osteogenic cells and sodium alginate/gelatin (2:3) scaffold presented fine biocompatibility following cross-linking with 0.6% of CaCl(2). After implantation, the scaffold-cell construct promoted both ectopic bone formation and bone healing in the rabbit calvarial critical-sized defect model. Our data demonstrated that the sodium alginate/gelatin scaffold could be a suitable biomaterial for bone engineering, and the scaffold-osteogenic cells construct is a promising alternative approach for the bone healing process.     

In vivo bone tissue engineering using mesenchymal stem cells on a novel electrospun nanofibrous scaffold

The objective of this study was to assess bone formation from mesenchymal stem cells (MSCs) on a novel nanofibrous scaffold in a rat model. A highly porous, degradable poly(epsilon-caprolactone) (PCL) scaffold with an extracellular matrix-like topography was produced by electrostatic fiber spinning. MSCs derived from the bone marrow of neonatal rats were cultured, expanded, and seeded on the scaffolds. The cell-polymer constructs were cultured with osteogenic supplements in a rotating bioreactor for 4 weeks, and subsequently implanted in the omenta of rats for 4 weeks. The constructs were explanted and characterized by histology, immunohistochemistry, and scanning electron microscopy. The constructs maintained the size and shape of the original scaffolds. Morphologically, the constructs were rigid and had a bone-like appearance. Cells and extracellular matrix (ECM) formation were observed throughout the constructs. In addition, mineralization and type I collagen were also detected. This study establishes the ability to develop bone grafts on electrospun nanofibrous scaffolds in a well-vascularized site using MSCs.     

脂肪源干细胞与聚丙烯网片的生物相容性研究

目的观察脂肪源干细胞(ADSCs)与聚丙烯网片的生物相容性。方法制备兔ADSCs悬液。取聚丙烯网片浸提液培养ADSCs。用四甲基偶氮唑盐(MTT)法检测细胞活力,评价支架细胞毒性。ADSCs传代扩增后,接种到聚丙烯网片支架上,体外培养1周。用扫描电子显微镜观察细胞在支架上黏附生长及增殖。结果 ADSCs在聚丙烯网片浸提液中可保持较高的增殖率(RGR)(24、48、72 h实验组细胞RGR分别为97%、96%、101%,平均RGR为103.5%),与对照组比较,差异无统计学意义(χ2=17.45,P0.05),聚丙烯网片浸提液无细胞毒性。脂肪干细胞种植于两种支架材料后生长速度快,扫描电子显微镜观察可见脂肪干细胞呈球型,并伸展形成伪足,贴附于支架材料,细胞间相互连接成团。结论聚丙烯网片支架与ADSCs具有良好的生物相容性,无细胞毒性,可作为脂肪组织工程较理想的生物支架材料。     

Nonintegrating knockdown and customized scaffold design enhances human adipose-derived stem cells in skeletal repair

An urgent need exists in clinical medicine for suitable alternatives to available techniques for bone tissue repair. Human adipose-derived stem cells (hASCs) represent a readily available, autogenous cell source with well-documented in vivo osteogenic potential. In this article, we manipulated Noggin expression levels in hASCs using lentiviral and nonintegrating minicircle short hairpin ribonucleic acid (shRNA) methodologies in vitro and in vivo to enhance hASC osteogenesis. Human ASCs with Noggin knockdown showed significantly increased bone morphogenetic protein (BMP) signaling and osteogenic differentiation both in vitro and in vivo, and when placed onto a BMP-releasing scaffold embedded with lentiviral Noggin shRNA particles, hASCs more rapidly healed mouse calvarial defects. This study therefore suggests that genetic targeting of hASCs combined with custom scaffold design can optimize hASCs for skeletal regenerative medicine.     

Composite hydrogel scaffolds incorporating decellularized adipose tissue for soft tissue engineering with adipose-derived stem cells

An injectable tissue-engineered adipose substitute that could be used to deliver adipose-derived stem cells (ASCs), filling irregular defects and stimulating natural soft tissue regeneration, would have significant value in plastic and reconstructive surgery. With this focus, the primary aim of the current study was to characterize the response of human ASCs encapsulated within three-dimensional bioscaffolds incorporating decellularized adipose tissue (DAT) as a bioactive matrix within photo-cross-linkable methacrylated glycol chitosan (MGC) or methacrylated chondroitin sulphate (MCS) delivery vehicles. Stable MGC- and MCS-based composite scaffolds were fabricated containing up to 5 wt% cryomilled DAT through initiation with long-wavelength ultraviolet light. The encapsulation strategy allows for tuning of the 3-D microenvironment and provides an effective method of cell delivery with high seeding efficiency and uniformity, which could be adapted as a minimally-invasive in situ approach. Through in vitro cell culture studies, human ASCs were assessed over 14 days in terms of viability, glycerol-3-phosphate dehydrogenase (GPDH) enzyme activity, adipogenic gene expression and intracellular lipid accumulation. In all of the composites, the DAT functioned as a cell-supportive matrix that enhanced ASC viability, retention and adipogenesis within the gels. The choice of hydrogel also influenced the cell response, with significantly higher viability and adipogenic differentiation observed in the MCS composites containing 5 wt% DAT. In vivo analysis in a subcutaneous Wistar rat model at 1, 4 and 12 weeks showed superior implant integration and adipogenesis in the MCS-based composites, with allogenic ASCs promoting cell infiltration, angiogenesis and ultimately, fat formation.