Yangzi Jiang

In vivo restoration of full-thickness cartilage defects by poly(lactide-co-glycolide) sponges filled with fibrin gel, bone marrow mesenchymal stem cells and DNA complexes

A composite construct comprising of bone marrow mesenchymal stem cells (BMSCs), plasmid DNA encoding transforming growth factor-beta1 (pDNA-TGF-beta1), fibrin gel and poly (lactide-co-glycolide) (PLGA) sponge was designed and employed to repair articular cartilage defects. To improve the gene transfection efficiency, a cationized chitosan derivative N,N,N-trimethyl chitosan chloride (TMC) was employed as the vector. The TMC/DNA complexes had a transfection efficiency of 9% to BMSCs and showed heterogeneous TGF-beta1 expression in a 10-day culture period in vitro. In vivo culture of the composite constructs was performed by implantation into full-thickness cartilage defects of New Zealand white rabbit joints, using the constructs absence of pDNA-TGF-beta1 or BMSCs as controls. Heterogeneous expression of TGF-beta1 in vivo was detected at 4 weeks, but its level was decreased in comparison with that of 2 weeks. After implantation for 12 weeks, the cartilage defects were successfully repaired by the composite constructs of the experimental group, and the neo-cartilage integrated well with its surrounding tissue and subchondral bone. Immunohistochemical and glycosaminoglycans (GAGs) staining confirmed the similar amount and distribution of collagen type II and GAGs in the regenerated cartilage as that of hyaline cartilage. The cartilage special genes expressed in the neo-tissue were closer to those of the normal cartilage. An overall score of 2.83 was obtained according to Wakitanis standard. By contrast, only part of the defects was repaired by the pDNA-TGF-beta1 absence constructs, and no cartilage repair but fibrous tissue was found for the BMSCs absence constructs. Therefore, combination of the PLGA sponge/fibrin gel scaffold with BMSCs and gene therapy is an effective method to restore cartilage defects and may have a great potential for practical applications in the near future.

The restoration of full-thickness cartilage defects with BMSCs and TGF-beta 1 loaded PLGA/fibrin gel constructs.

Poly(lactide-co-glycolide) (PLGA) sponge was filled with fibrin gel, bone marrow mesenchymal stem cells (BMSCs) and transforming growth factor-β1 (TGF-β1) to obtain a construct for cartilage restoration in vivo. The PLGA sponge lost its weight steadily in vitro, but degraded much faster in the construct of PLGA/fibrin gel/BMSCs implanted in the full-thickness cartilage defects. The in vivo degradation of the fibrin gel inside the construct was prolonged to 12 wk too. The CM-DiI labeled allogenic BMSCs were detectable after transplantation (implantation) into the defects for 12 wk by small animal in vivo fluorescence imaging and confocal laser scanning microscopy. In vivo repair experiments were firstly performed by implantation of the PLGA/fibrin gel/BMSCs and PLGA/BMSCs constructs into full-thickness cartilage defects (3 mm in diameter and 4 mm in depth) of New Zealand white rabbits for 12 wk. The defects implanted with the PLGA/fibrin gel/BMSCs constructs were filled with cartilage-like tissue containing collagen type II and glycosaminoglycans (GAGs), while those by the PLGA/BMSCs constructs were filled with fibrous-like tissues. To repair the defects of larger size (4 mm in diameter), addition of growth factors was mandatory as exemplified here by further loading of TGF-β1. Implantation of the PLGA/fibrin gel/BMSCs/TGF-β1 constructs into the full-thickness cartilage defects for 12 wk resulted in full restoration of the osteochondral tissue. The neo-cartilage integrated well with its surrounding cartilage and subchondral bone. Immunohistochemical and GAGs staining confirmed the similar distribution of collagen type II and GAGs in the regenerated cartilage as that of hyaline cartilage. The quantitative reverse transcription-polymerase chain reaction (qRT-PCR) revealed that the cartilage special genes were significantly up-regulated compared with those of the TGF-β1 absent constructs.

Mesenchymal stem cell seeded knitted silk sling for the treatment of stress urinary incontinence.

Stress urinary incontinence remains a worldwide problem affecting patients of all ages. Implantation of suburethral sling is the cornerstone treatment. Current slings have inherent disadvantages. This study aims to develop a tissue engineered sling with bone marrow derived mesenchymal stem cell seeded degradable silk scaffold. The mesenchymal stem cells were obtained from Sprague-Dawley rats and were characterized in vitro. Layered cell sheets were formed after two weeks of culture and were labeled with carboxyfluorescein diacetate. Forty female rats were divided into four groups: Group A (n=5) had sham operation; other three groups underwent bilateral proximal sciatic nerve transection and were confirmed with stress urinary incontinence by the leak-point pressure measurement at 4 weeks after operation. Then, Group B (n=5) had no sling placed; Group C (n=15) was treated with a silk sling; and Group D (n=15) was treated with the tissue engineered sling. Histology and the leak-point pressure measurements were done at 4 and 12 weeks after the sling implantation while collagen content and mechanical testing were done at 12 weeks. The results showed that Group B had a significantly lower leak-point pressure (24.0+/-4.2 cmH(2)O) at 4 weeks (P<0.05), while Group C (38.0+/-3.3 cmH(2)O) and Group D (36.3+/-3.1 cmH(2)O) almost reached to the normal level shown by Group A (41.6+/-3.8 cmH(2)O) (p>0.05). At 12 weeks, tissue engineered sling of group D has higher collagen content (70.84+/-14.49 microg/mg) and failure force (2.436+/-0.192 N) when compared those of Group C (38.94+/-7.05 microg/mg and 1.521+/-0.087 N) (p<0.05). Both the silk sling and tissue engineered sling showed convincing functional effects for the treatment of stress urinary incontinence in a rat model. And the better ligament-like tissue formation in the tissue engineered sling suggested potential long-term function.

Origin and function of cartilage stem/progenitor cells in osteoarthritis

Articular cartilage is a physiologically non-self-renewing avascular tissue with a singular cell type, the chondrocyte, which functions as the load-bearing surface of the arthrodial joint. Injury to cartilage often progresses spatiotemporally from the articular surface to the subchondral bone, leading to development of degenerative joint diseases such as osteoarthritis (OA). Although lacking intrinsic reparative ability, articular cartilage has been shown to contain a population of stem cells or progenitor cells, similar to those found in many other adult tissues, that are thought to be involved in the maintenance of tissue homeostasis. These so-called cartilage-derived stem/progenitor cells (CSPCs) have been observed in human, equine and bovine articular cartilage, and have been identified, isolated and characterized on the basis of expression of stem-cell-related surface markers, clonogenicity and multilineage differentiation ability. However, the origin and functions of CSPCs are incompletely understood. We review here the current status of CSPC research and discuss the possible origin of these cells, what role they might have in cartilage repair, and their therapeutic potential in OA.

The use of type 1 collagen scaffold containing stromal cell-derived factor-1 to create a matrix environment conducive to partial-thickness cartilage defects repair

Despite the presence of cartilage-derived mesenchymal stem cells (C-MSCs) and synovial membrane-derived mesenchymal stem cells (SM-MSCs) populations, partial-thickness cartilage defects, in contrast to the full-thickness defects, are devoid of spontaneous repair capacity. This study aims to create an in situ matrix environment conducive to C-MSCs and SM-MSCs to promote cartilage self-repair. Spontaneous repair with MSCs migration into the defect area was observed in full-thickness defects, but not in partial-thickness defects in rabbit model. Exxa0vivo and inxa0vitro studies showed that subchondral bone or type 1 collagen (col1) scaffold was more permissive for MSCs adhesion than cartilage or type 2 collagen (col2) scaffold and induced robust stromal cell-derived factors-1 (SDF-1) dependent migration of MSCs. Furthermore, creating a matrix environment with col1 scaffold containing SDF-1 enhanced in situ self-repair of partial-thickness defects in rabbit 6 weeks post-injury. Hence, the inferior self-repair capacity in partial-thickness defects is partially owing to the non-permissive matrix environment. Creating an in situ matrix environment conducive to C-MSCs and SM-MSCs migration and adhesion with col1 scaffold containing SDF-1 can be exploited to improve self-repair capacity of cartilage.

Local delivery of autologous platelet in collagen matrix simulated in situ articular cartilage repair.

Bone marrow released by microfracture or full-thickness cartilage defect can initiate the in situ cartilage repair. However, it can only repair small cartilage defects (<2 cm2). This study aimed to investigate whether autologous platelet-rich plasma (PRP) transplantation in collagen matrix can improve the in situ bone marrow-initiated cartilage repair. Full-thickness cartilage defects (diameter 4 mm, thickness 3 mm) in the patellar grooves of male New Zealand White rabbits were chosen as a model of in situ cartilage repair. They were treated with bilayer collagen scaffold (group II), PRP and bilayer collagen scaffold (group III), and untreated (group I), respectively (n = 11). The rabbits were sacrificed at 6 and 12 weeks after operation. The repaired tissues were processed for histology and for mechanical test. The results showed that at both 6 and 12 weeks, group III had the largest amounts of cartilage tissue, which restored a larger surface area of the cartilage defects. Moreover, group III had higher histological scores and more glycosaminoglycans (GAGs) content than those in the other two groups (p < 0.05). The Youngs modulus of the repaired tissue in group II and group III was higher than that of group I (p < 0.05). Autologous PRP and bilayer collagen matrix stimulated the formation of cartilage tissues. The findings implicated that the combination of PRP with collagen matrix may repair larger cartilage defects that currently require complex autologous chondrocyte implantation (ACI) or osteochondral grafting.

Novel biodegradable three-dimensional macroporous scaffold using aligned electrospun nanofibrous yarns for bone tissue engineering.

This study aimed to develop a practical three-dimensional (3D) macroporous scaffold from aligned electrospun nanofibrous yarns for bone tissue engineering. A novel 3D unwoven macroporous nanofibrous (MNF) scaffold was manufactured with electrospun poly(L-lactic acid) and polycaprolactone (w/w 9:1) nanofibers through sequential yarns manufacture and honeycombing process at 65°C. The efficacy of 3D MNF scaffold for bone formation were evaluated using human embryonic stem cell-derived mesenchymal stem cells (hESC-MSCs) differentiation model and rabbit tibia bone defect model. In vitro, more cell proliferation and cell ingrowth were observed in 3D MNF scaffold. Moreover, calcium deposit was obviously detected in vitro differentiation of hESC-MSCs. In vivo, histology and X-ray showed that 3D MNF scaffold treated bone defect had fine 3D bony tissue formation around the scaffold as well as inside the scaffold at 3 weeks and 6 weeks. This study demonstrated that 3D MNF scaffold provides a structural support for hESC-MSCs growth and guides bone formation suggesting that this novel strategy successfully makes use of electrospun fibers for bone tissue engineering, which may help realize the clinical translation of electrospun nanofibers for regenerative medicine in future.

Bi-layer collagen/microporous electrospun nanofiber scaffold improves the osteochondral regeneration.

An optimal scaffold is crucial for osteochondral regeneration. Collagen and electrospun nanofibers have been demonstrated to facilitate cartilage and bone regeneration, respectively. However, the effect of combining collagen and electrospun nanofibers on osteochondral regeneration has yet to be evaluated. Here, we report that the combination of collagen and electrospun poly-l-lactic acid nanofibers synergistically promotes osteochondral regeneration. We first fabricated bi-layer microporous scaffold with collagen and electrospun poly-l-lactic acid nanofibers (COL-nanofiber). Mesenchymal stem cells were cultured on the bi-layer scaffold and their adhesion, proliferation and differentiation were examined. Moreover, osteochondral defects were created in rabbits and implanted with COL-nanofiber scaffold. Cartilage and subchondral bone regeneration were evaluated at 6 and 12weeks after surgery. Compared with COL scaffold, cells on COL-nanofiber scaffold exhibited more robust osteogenic differentiation, indicated by higher expression levels of OCN and runx2 genes as well as the accumulation of calcium nodules. Furthermore, implantation of COL-nanofiber scaffold seeded with cells induced more rapid subchondral bone emergence, and better cartilage formation, which led to better functional repair of osteochondral defects as manifested by histological staining, biomechanical test and micro-computed tomography data. Our study underscores the potential of using the bi-layer microporous COL-nanofiber scaffold for the treatment of deep osteochondral defects.

A novel strategy incorporated the power of mesenchymal stem cells to allografts for segmental bone tissue engineering.

Mesenchymal stem cells (MSCs) hold great promise for bone regeneration. However, the power of mesenchymal stem cells has not been applied to structural bone allografts in clinical practice. This study designed a new strategy to enhance the efficiency of allografts for segmental bone regeneration. Isolated MSCs were cultured to form a cell sheet. The MSC sheet was then wrapped onto structural allografts. The assembled structures were cultured in vitro to evaluate the differentiation potential of MSC sheet. The assembled structures were implanted subcutaneously into nude mice as well as into the segmental radius defect of rabbits to investigate the efficiency of MSC sheets to repopulate allografts for bone repair. MSC sheets, upon assembling on bone grafts, showed similar differentiation properties to the in situ periosteum in vitro. After implantation the MSC sheets accelerated the repopulation of bone grafts in nude mice. Moreover, MSC sheets induced thicker cortical bone formation and more efficient graft-to-bone end fusion at the segmental bone defects in rabbits. This study thus presented a novel, more efficient, and practical strategy for large weight-bearing bone reconstruction by using MSC sheets to deliver large number of MSCs to repopulate the bone allografts.

Cell transplantation for articular cartilage defects: principles of past, present, and future practice.

As articular cartilage has very limited self-repair capability, the repair and regeneration of damaged cartilage is a major challenge. This review aims to outline the past, present, and future of cell therapies for articular cartilage defect repair. Autologous chondrocyte implantation (ACI) has been used clinically for more than 20 years, and the short, medium, and long-term clinical outcomes of three generation of ACI are extensively overviewed. Also, strategies of clinical outcome evaluation, ACI limitations, and the comparison of ACI clinical outcomes with those of other surgical techniques are discussed. Moreover, mesenchymal stem cells and pluripotent stem cells for cartilage regeneration in vitro, in vivo, and in a few clinical studies are reviewed. This review not only comprehensively analyzes the ACI clinical data but also considers the findings from state-of-the-art stem cell research on cartilage repair from bench and bedside. The conclusion provides clues for the future development of strategies for cartilage regeneration.