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.

Neonatal desensitization supports long-term survival and functional integration of human embryonic stem cell-derived mesenchymal stem cells in rat joint cartilage without immunosuppression.

Immunological response hampers the investigation of human embryonic stem cells (hESCs) or their derivates for tissue regeneration in vivo. Immunosuppression is often used after surgery, but exhibits side effects of significant weight loss and allows only short-term observation. The purpose of this study was to investigate whether neonatal desensitization supports relative long-term survival of hESC-derived mesenchymal stem cells (hESC-MSCs) and promotes cartilage regeneration. hESC-MSCs were injected on the day of birth in rats. Six weeks after neonatal injection, a full-thickness cylindrical cartilage defect was created and transplanted with a hESC-MSC-seeded collagen bilayer scaffold (group d+s+c) or a collagen bilayer scaffold (group d+s). Rats without neonatal injection were transplanted with the hESC-MSC-seeded collagen bilayer scaffold to serve as controls (group s+c). Cartilage regeneration was evaluated by histological analysis, immunohistochemical staining, and biomechanical test. The role of hESC-MSCs in cartilage regeneration was analyzed by CD4 immunostaining, cell death detection, and visualization of human cells in regenerated tissues. hESC-MSCs expressed CD105, CD73, CD90, CD29, and CD44, but not CD45 and CD34, and possessed trilineage differentiation potential. Group d+s+c exhibited greater International Cartilage Repair Society (ICRS) scores than group d+s or group s+c. Abundant collagen type II and improved mechanical properties were detected in group d+s+c. There were less CD4+ inflammatory cell infiltration and cell death at week 1, and hESC-MSCs were found to survive as long as 8 weeks after transplantation in group d+s+c. Our study suggests that neonatal desensitization before transplantation may be an efficient way to develop a powerful tool for preclinical study of human cell-based therapies in animal models.

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.

Platelet-mediated mesenchymal stem cells homing to the lung reduces monocrotaline-induced rat pulmonary hypertension.

Bone marrow mesenchymal stem cell (BM-MSC) transplantation has been suggested to be a promising method for the treatment of pulmonary arterial hypertension (PAH), a fatal disease currently without effective preventive/therapeutic strategies. However, the detailed mechanisms underlying BM-MSC therapy are largely unknown. We designed the present study to test the hypothesis that circulating platelets facilitate BM-MSC homing to the lung vasculature in a rat model of PAH induced by monocrotalin (MCT). A single subcutaneous administration of MCT induced a marked rise in right ventricular systolic pressure (RVSP) and the weight ratio of right to left ventricle plus septum (RV/LV+S) 3 weeks after injection. The injection of MSCs via tail vein 3 days after MCT significantly reduced the increase of RVSP and RV/LV+S. The fluorescence-labeled MSCs injected into the PAH rat circulation were found mostly distributed in the lungs, particularly on the pulmonary vascular wall, whereas cell homing was abolished by an anti-P-selectin antibody and the GPIIb/IIIa inhibitor tirofiban. Furthermore, using an in vitro flow chamber, we demonstrated that MSC adhesion to the major extracellular matrix collagen was facilitated by platelets and their P-selectin and GPIIb/IIIa. Therefore, the current study suggested that platelet-mediated MSC homing prevented the aggravation of MCT-induced rat PAH, via P-selectin and GPIIb/IIIa-mediated mechanisms.

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.

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.

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.

Specific interactions between human fibroblasts and particular chondroitin sulfate molecules for wound healing.

The chondroitin sulfates (CSs) constitute an important group of biomacromolecules in the extracellular matrix. However, limited information is available about their specific biological functions. This study aimed to define the interactions between cells and various types of CS. The effects of CSs on cellular activities and the cell cycle were evaluated using cell culture, RNA interference, real-time polymerase chain reaction, flow cytometry, wound healing and contraction models. The results showed that C-6-S promoted both cell proliferation and adhesion, while C-4-S promoted proliferation but inhibited adhesion. Moreover, knockdown of chondroitin inhibited cell proliferation and migration, as well as arresting cells in the G(2)/M phase. Also, both C-4-S and C-6-S promoted wound closure in a two-dimensional wound model, whereas only C-6-S inhibited wound contraction in a three-dimensional wound model. This study illustrates that the interaction between cells and different CSs are specific and sulfate-group-dependent. These findings provide useful information for better applications of CSs for wound healing.

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 cm(2)). 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 Young's 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.