Effects of low-intensity ultrasound on chondrogenic differentiation of mesenchymal stem cells embedded in polyglycolic acid: an in vivo study

In this study we investigated the effects of LIUS on chondrogenic differentiation of bone marrow-derived mesenchymal stem cells (BM-MSC). Our hypothesis is that LIUS may be a noninvasively effective stimulant to a biological system in vivo by turning on differentiation of MSCs and promotion of chondrogenesis. MSCs were isolated from the bone marrow of New Zealand white rabbits and cultured in monolayer for 2 weeks. They were then harvested and seeded into polyglycolic acid (PGA) non-woven mesh at a number of 5 x 10(6) cells. Cultured with a chondrogenic-defined media for 1 week, the PGA/MSCs constructs (n = 4) were implanted subcutaneously in the back of nude mice (n = 9, each group). The ultrasound (US) group received US stimulation at a frequency of 0.8 MHz and intensity of 200 mW/cm(2) for 10 min every day up to 4 weeks, while the control group had no US stimulation. Analyses of histological, immunohistochemical, biochemical, and mechanical characteristics were made at 1, 2, and 4 weeks post-stimulation, respectively. Total DNA contents showed no significant difference between the two groups. Total collagen and glycosaminoglycan (GAG) increased more significantly in the US-stimulated group than in the control. Histology of Safranin O/Fast green confirmed more intense and spreading extracellular matrix (ECM) at 2 and 4 weeks in the US-stimulated specimens. Mechanical tests exhibited that compressive strengths were also significantly higher in the US-stimulated cells at later times. This study strongly suggests that it may be possible for ultrasound to have some stimulatory effects in vivo on the chondrogenesis of MSCs.     

Engineered mesenchymal stem cells for cartilage repair

Healthy cartilage is a highly robust tissue, and is resilient against the stringent mechanical and biological constraints imposed upon it. Cartilage defects are common features of joint diseases, but current treatments can rarely restore the full function of native cartilage. Recent studies have provided new perspectives for cartilage engineering using mesenchymal stem cells (MSCs). However, the sequential events occurring during chondrogenesis must be fully understood before we are able to reproduce faithfully the complex molecular events that lead to MSC differentiation and long-term maintenance of cartilage characteristics. Here, we focus on the potential of MSCs to repair cartilage with an emphasis on the factors that are known to be required in inducing chondrogenesis.     

Original approach for cartilage tissue engineering with mesenchymal stem cells

Cartilage tissue engineering gives the ability to product adaptable neocartilage to lesion with autologous cells. Our work aimed to develop a stratified scaffold with a simple and progressive spraying build-up to mimic articular cartilage environment. An Alginate/Hyaluronic Acid (Alg/HA) hydrogel seeded with human Mesenchymal Stem Cells (hMSC) was construct by spray. First, cells repartition and actin organization were study with confocal microscopy. Then, we analyzed cells viability and finally, metabolic activity. Our results indicated a homogenous cells repartition in the hydrogel and a pericellular actin repartition. After 3 days of culture, we observed about 52% of viable cells in the scaffold. Then, from day 7 until the end of culture (D28), the proportion of living cells and their metabolic activity increased, what indicates that culture conditions are not harmful for the cells. We report here that sprayed method allowed to product a scaffold with hMSCs that confer a favorable environment for neocartilage construction: 3D conformation and ability of cells to increase their metabolic activity, therefore with few impact on hMSCs.     

滑膜间充质干细胞修复膝关节软骨损伤的应用与进展

背景：膝关节软骨损伤后很难愈合,是临床上亟需解决的重要课题。目的：总结滑膜间充质干细胞在膝关节软骨损伤治疗上的优越性。方法：用英文主题词“Knee Joint, Cartilage, Synovial Membrane, Tissues, Injuries, Repair”在PubMed数据库中检索2005年8月至2015年8月文献总共625篇。采纳并分析滑膜间充质干细胞治疗膝关节软骨损伤文献48篇。排除其他非滑膜间充质干细胞及非膝关节软骨损伤治疗的相关文章,保留35篇文章进行综述。结果与结论：应用滑膜间充质干细胞治疗膝关节软骨损伤,能够获得更加理想的治疗效果,损伤组织本身固有的间充质干细胞是修复损伤组织的最佳种子细胞。中国组织工程研究杂志出版内容重点：干细胞;骨髓干细胞;造血干细胞;脂肪干细胞;肿瘤干细胞;胚胎干细胞;脐带脐血干细胞;干细胞诱导;干细胞分化;组织工程     

Genetic modification of mesenchymal stem cells for cartilage repair

Reproduction of a native, functional architecture in articular cartilage defects is a major problem in orthopaedic surgery. The elaboration of workable options to heal damaged cartilage might necessitate to involve cellular, molecular and environmental components to allow for the formation of an adequate and stable repair tissue in sites of injury. Strategies based on the transfer of candidate sequences to progenitor cells offer powerful tools to achieve this goal. The aim of this report is to provide an overview of the most recent therapeutic approaches developed in experimental orthopaedic research.     

The in vivo bone formation by mesenchymal stem cells in zein scaffolds

In our previous study, a three-dimensional zein porous scaffold was prepared. This scaffold showed proper mechanical properties, good biocompatibility, and controllable biodegradation. In addition, it allowed blood vessels to form inside in vivo. In the current study, we prepared the complexes of zein scaffolds and rabbit MSCs, and investigated ectopic bone formation in nude mice. Furthermore, we implanted them into the radius defects of rabbits and assessed whether they could be helpful in the repair of critical-sized bone defects. The results showed that the complexes of zein scaffolds and rabbit MSCs could undergo ectopic bone formation in the thigh muscle pouches of nude mice. More importantly, the complexes could lead to the repair of critical-sized radius defects in rabbits accompanied with blood vessels' formation, which clearly demonstrates promise for the treatment of bone defects through tissue engineering.     

低强度脉冲式超声对关节软骨的修复

BACKGROUND: Articular cartilage injuries can result from a variety of causes. Conventional therapy cannot obtain the optimal clinical results. Low-intensity pulsed ultrasound has been shown to promote the repair of injured articular cartilage. OBJECTIVE: To investigate the effects of low-intensity pulsed ultrasound on the repair of injured articular cartilage. METHODS: Twenty New Zealand white rabbits were used to establish knee arthritis models and equally randomized into study and control groups, respectively. Rabbits in the study group received low-intensity pulsed ultrasound treatment, and sham low-intensity pulsed ultrasound treatment was given in the control group. At 8 weeks after treatment, pathological change and histological scores in articular cartilage tissue collected from both groups were determined. Moreover, the ultrastructure and type II collagen expression of chondrocytes were determined. Matrix metalloproteinase-13 mRNA expression was detected by quantitative real-time PCR. RESULTS AND CONCLUSION: At 8 weeks after treatment, toluidine blue staining showed a disordered arrangement of cells, decreased number of cartilage cells in each layer and cluster in the control group. Light disordered arrangement of cells, decreased appearance of the superficial layer cells and the cluster phenomenon were observed in the study group. Articular cartilage tissue scores were significantly decreased in the study group compared with the control group (P < 0.05). The chondrocytes were small, enlarged intracellular mitochondria and rough endoplasmic reticulum, cytoplasmic swelling, collagen fibrils coarse, well developed Golgi apparatus, and nuclear fragmentation were observed in the control group. In addition, the normal structure of organelles disappeared and cell degeneration was observed in the control group. In the study group, the size of chondrocytes and the Golgi complex and other organelles were normal, and the protein polysaccharide granules were observed in the cytoplasm and membrane. The mRNA expression of matrix metalloproteinase-13 in the study group was significantly lower than that in the control group (P < 0.05). Type II collagen immunoreactivity in the study group was stronger than that in the control group. No incision infection, suppuration, red swelling appeared in all rabbits. Our results suggest that low-intensity pulsed ultrasound can be used for the treatment of articular cartilage injury by alleviating the degradation of collagen type II and inhibiting the expression of matrix metalloproteinase-13. 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     

骨髓间充质干细胞修复软骨缺损的应用前景

背景：骨髓间充质干细胞是一种非造血性成体干细胞,主要存在于骨髓,具有很强的增殖能力和多向分化潜能,临床应用前景广阔。 目的：对促进骨髓间充质干细胞向软骨细胞分化的生长因子、生物支架等方面的最新研究进展进行综述。 方法：以“cartilage defects,tissue engineering,biological scaffolds,bone marrow mesenchymal stem cells,cytokines”和“软骨缺损,组织工程,生物支架,骨髓间充质干细胞,细胞因子 ”为检索词,由第一作者检索1990至2014年PubMed和中国知网数据库,查阅近年骨髓间充质干细胞向软骨细胞分化的相关文献,最终保留51篇文献进行分析。 结果与结论：骨髓间充质干细胞具有向软骨细胞分化的潜能,目前许多细胞因子可以促进骨髓间充质干细胞向软骨细胞分化,很多生物支架可以作为骨髓间充质干细胞向软骨细胞分化的载体。但是骨髓间充质干细胞向软骨细胞分化的研究还在探索过程中,真正进入临床还有许多亟待解决和深入探究的问题。     

骨髓间充质干细胞于软骨组织工程的应用

关节软骨缺损在骨科临床十分常见,目前临床修复软骨缺损的方法很多,但是由于各自固有的缺陷难以达到满意的临床效果,因此探索软骨缺损的修复方法一直是人们不断深入研究的课题。软骨组织工程的发展为软骨缺损的修复提供了新的途径。种子细胞和支架材料是软骨组织的两个基本要素,根据近年来软骨组织工程的研究进展和方向,从骨髓间充质干细胞的诱导方式、诱导机制及研究进展方面进行探讨,证明骨髓间充质干细胞作为种子细胞构建组织工程软骨的优越性。     

骨髓间充质干细胞与壳聚糖复合修复关节软骨损伤

背景：创伤等导致的关节软骨缺损是国内外骨科界面临的难题,组织工程学技术为软骨缺损的修复提供了新方法。 目的：探讨壳聚糖-骨髓间充质干细胞复合材料修复兔膝关节软骨缺损的可行性。 方法：将培养的兔骨髓间充质干细胞种植到壳聚糖支架上体外构建壳聚糖-骨髓间充质干细胞复合材料,移植到兔关节软骨缺损处为实验组,不予以特殊处理为对照组。术后6,12周,大体观察以及甲苯胺蓝染色评定两组软骨组织修复情况。 结果与结论：术后6周,对照组仅有纤维组织增生,实验组关节软骨缺损处有软骨样组织生成。术后12周,对照组软骨缺损边缘可观察到少量类透明软骨组织,实验组缺损区完全覆盖有光滑、透明软骨组织。术后12 周,对照组甲苯胺蓝染色较淡,有少量软骨组织生成,实验组甲苯胺蓝染色较明显,缺损完全被透明软骨组织所覆盖,软骨细胞较多。结果表明兔骨髓间充质干细胞-壳聚糖支架复合材料能更好的引导软骨组织的生成,促进软骨缺损修复。 中国组织工程研究杂志出版内容重点：干细胞;骨髓干细胞;造血干细胞;脂肪干细胞;肿瘤干细胞;胚胎干细胞;脐带脐血干细胞;干细胞诱导;干细胞分化;组织工程     

不同预处理策略促进间充质干细胞的归巢

BACKGROUND:Homing is the initial and key procedure of stem cells-based tissue restoration. Current studies have shown that the inability to recruit bone marrow mesenchymal stem cells to target tissue with high efficiency remains a significant barrier to tissue restoration. Preconditioning strategy provides a new insight to promote stem cell homing. OBJECTIVE:To review preconditioning strategies for promoting the homing of stem cells. METHODS:In PubMed database, different combinations of terms from “stem cell, mesenchymal stem cells, preconditioning, homing, migration” served as search terms to retrieve articles referring preconditioning strategies for promoting mesenchymal stem cell homing published from January 2000 to September 2015. According to the inclusion criteria, 72 articles were selected for final review. RESULTS AND CONCLUSION:Pretreating target tissue or mesenchymal stem cells ahead of cell transplantation, known as tissue preconditioning or cell preconditioning, prominently promotes the homing of mesenchymal stem cells, therefore enhancing tissue restoration effect. Tissue preconditioning is designed to up-regulate expression of chemokines by varying the local microenvironment, thereby increasing homing ability of mesechymal stem cells. Mesenchymal stem cell preconditioning strategies, for example, gene modification and cytokine induction, are mainly to up-regulate expression of chemokine receptors on the surface of mesenchymal stem cells as effectors, and thus promote targeted cell homing. Overall, preconditioning strategy will bring great hope to apply stem cell therapy into the clinic.     

A cartilage ECM-derived 3-D porous acellular matrix scaffold for in vivo cartilage tissue engineering with PKH26-labeled chondrogenic bone marrow-derived mesenchymal stem cells

We developed a natural, acellular, 3-D interconnected porous scaffold derived from cartilage extracellular matrix (ECM). Human cartilage was physically shattered, then decellularized sequentially with use of hypotonic buffer, TritonX-100, and a nuclease solution and made into a suspension. The scaffold was fabricated by simple freeze-drying and cross-linking techniques. On histology, scaffolds showed most of the ECM components after removal of the cell fragments, and scanning electron microscopy revealed a 3-D interconnected porous structure. Cellular viability assay revealed no cytotoxic effects. In vitro study showed that the novel scaffold could provide a suitable 3-D environment to support the adheration, proliferation and differentiation of bone marrow-derived mesenchymal stem cells (BMSCs) to chondrocytes in culture with chondrogenic medium after 21 days. Chondrogenically induced BMSCs labeled with fluorescent dye PKH26 were then grown on scaffolds and implanted subcutaneously into nude mice. Four weeks later, cartilage-like tissue formed, with positive staining for Safranin O, tuoluidine blue and collagen II. Cells in the samples seemed to confirm that they originated from the labeled BMSCs, as confirmed by in vivo fluorescent imaging and immunofluorescence examination. In conclusion, the cartilage ECM-derived porous scaffold shows potential as biomaterial for cartilage tissue engineering, and PKH26 fluorescent labeling and in vivo fluorescent imaging can be useful for cell tracking and analyzing cell-scaffold constructs in vivo.     

基因修饰骨髓间充质干细胞修复关节软骨损伤

背景：随着生物技术的发展,通过转基因技术修饰细胞,从而获得长期稳定表达的生物活性因子以治疗关节软骨损伤逐渐引起重视。 目的：就基因修饰的骨髓间充质干细胞在修复关节软骨损伤中的应用作一综述。 方法：由第一作者检索1990至2011年PubMed数据库(http://www.ncbi.nlm.nih.gov/PubMed)有关基因修饰骨髓间充质干细胞修复关节软骨损伤的文献,英文检索词为“cartilage,gene therapy,mesenchymal stem cells,tissue engineering,bioactive factor,vector”。共纳入15篇文献归纳总结。 结果与结论：骨髓间充质干细胞已被广泛应用于修复关节软骨损伤。通过转基因技术将特定外源基因导入骨髓间充质干细胞,联合细胞治疗和基因治疗可达到更好的治疗效果,在关节软骨损伤的治疗中有广阔的应用前景。     

Porous gelatin-chondroitin-hyaluronate tri-copolymer scaffold containing microspheres loaded with TGF-beta1 induces differentiation of mesenchymal stem cells in vivo for enhancing cartilage repair

The aim of the study was to produce a novel porous gelatin-chondroitin-hyaluronate scaffold in combination with a controlled release of transforming growth factor beta1 (TGF-beta1), which induced the differentiation of mesenchymal stem cells (MSCs) in vivo for enhancing cartilage repair. Gelatin microspheres loaded with TGF-beta1 (MS-TGFbeta1) showed a fast release at the initial phase (37.4%), and the ultimate accumulated release was 83.1% by day 18. The autologous MSCs seeded on MS-TGFbeta1/scaffold were implanted to repair full-thickness cartilage defects in rabbits as in vivo differentiation repair group, while MSCs differentiated in vitro were seeded on scaffold without MS-TGFbeta1 to repair the contra lateral cartilage defects (n = 30). Fifteen additional rabbits without treatment for defects were used as control. Histology observation showed that the in vivo differentiation repair group had better chondrocyte morphology, integration, continuous subchondral bone, and much thicker newly formed cartilage layer when compared to in vitro differentiation repair group 12 and 24 weeks, postoperatively. There was a significant difference in histological grading score between these two experimental groups, and both showed much better repair than that of the control. The present study implied that the novel scaffold with MS-TGFbeta1 might serve as a new way to induce the differentiation of MSCs in vivo to enhance the cartilage repair.     

Ectopic cartilage formation induced by mesenchymal stem cells on porous gelatin-chondroitin-hyaluronate scaffold containing microspheres loaded with TGF-beta1

The study aimed to produce a novel porous gelatin-chondroitin-hyaluronate scaffold in combination with a controlled release of TGF- beta1 and to evaluate its potentials in ectopic cartilage formation. The gelatin-chondroitin-hyaluronate scaffold was developed to mimic the natural extra cellular matrix of cartilage. Gelatin microspheres loaded with TGF- beta1 (MS-TGF beta1) showed a fast cytokine release at initial phase (37.4%) and the ultimate accumulated release was 83.1% by day 18. Then MS-TGF beta1 were incorporated into scaffold. The MSCs seeded on scaffold with or without MS-TGF beta1 were incubated in vitro or implanted subcutaneously in nude mice. In vitro study showed that, compared to the scaffold, the scaffold/MS-TGF beta1 significantly augmented the proliferation of MSCs and GAG synthesis. Three weeks postoperatively histology observation showed that in MSCs/scaffold/MS-TGF beta1 implantation group, cells of newly formed ectopic cartilage were located within typical lacunae and demonstrated morphological characteristics of chondrocytes. Six weeks later the ectopic cartilage grew more and islands of cartilage were observed. The matrix was extensively metachromatic by safranin-O/Fast green staining. Immunohistochemical staining also indicated ectopic cartilage was intensely stained for type II collagen. Instead, in the MSCs/scaffold implantation group, no cartilage-like tissue formed and matrix showed negative or weak positive staining. The percentage of positive staining area was significantly larger in MSCs/scaffold/MS-TGF beta1 group (p<0.05) at each time point. The results indicated that the novel gelatin-chondroitin-hyaluronate scaffold with MS-TGF beta1 could induce the chondral differentiation of MSCs to form cartilage and might serve as a new way to repair cartilage defects.     

骨髓基质干细胞在软骨组织工程中的应用

骨关节炎等损坏关节软骨的疾病严重影响人们的正常生活。骨髓基质干细胞具有较强的自我更新能力和多向分化潜能，在特定的诱导条件下分化为软骨细胞，为组织工程软骨修复软骨缺损带来希望。就骨髓基质干细胞分离、诱导分化为软骨细胞的方法、载体材料及目前存在的问题加以综述。     

骨髓基质干细胞在软骨组织工程中的应用

骨关节炎等损坏关节软骨的疾病严重影响人们的正常生活。骨髓基质干细胞具有较强的自我更新能力和多向分化潜能,在特定的诱导条件下分化为软骨细胞,为组织工程软骨修复软骨缺损带来希望。就骨髓基质干细胞分离、诱导分化为软骨细胞的方法、载体材料及目前存在的问题加以综述。     

骨髓间充质干细胞用于软骨组织工程的研究进展

细胞移植技术治疗软骨损伤已成为一项新兴的组织工程学研究热点.骨髓间充质干细胞由于其具有扩增快、便于分离提纯、可以体外诱导分化成为软骨细胞的特性,有可能成为组织工程化软骨的新型种子细胞.随着骨髓间充质干细胞应用于软骨组织工程研究的深入,结合近年的研究文献和成果,就骨髓间充质干细胞的诱导微环境和诱导方式的研究进展进行综述,探讨骨髓间充质干细胞作为种子细胞在构建组织工程软骨中的优越性.     

同种异体和异种来源骨髓间充质干细胞诱导成软骨修复喉软骨缺损

BACKGROUND: Because chondrocytes have no regeneration ability, to select suitable seed cells is the primary problem to repair cartilage defects. OBJECTIVE: To investigate the effect of allogeneic versus heterologous bone marrow mesenchymal stem cells (BMSCs) in repairing laryngeal cartilage defects after chondrogenic induction. METHODS: BMSCs from human and rabbits were isolated and cultured. Passage 3 cells were cultured in chondrogenic induction medium containing transforming transforming growth factor beta 1 and bone morphogenetic protein, and then were dropped onto a poly(lactic-co-glycolic acid) (PLGA) scaffold. Thirty New Zealand rabbits were randomly assigned into three groups: blank control group, human BMSCs group, rabbit BMSCs group. Animal models of laryngeal cartilage defects were made in the three groups. After modeling, saline-soaked PLGA scaffold, PLAG scaffold with human BMSCs or with rabbit BMSCs were implanted respectively into the rabbits in the normal blank, human BMSCs and rabbit BMSCs groups. The expression of type II collagen in the larynx and its surrounding tissues was detected by immunohistochemistry at 4 and 8 weeks postoperatively. RESULTS AND CONCLUSION: The animals in each group breathed normally with no presence of wheezing, and their eating and activity were good. Moreover, there was no purulency or infection in the three groups. At 4 and 8 weeks after operation, the positive rates of type II collagen in the two BMSCs groups were significantly higher than that in the blank control group (P < 0.05). There was no significant difference between two BMSCs groups (P > 0.05). These results show that both allogeneic and heterologous BMSCs have good therapeutic effects on the repair of laryngeal cartilage defects in rabbits.