Ectopic neocartilage formation from predifferentiated human adipose derived stem cells induced by adenoviral-mediated transfer of hTGF beta2.

Chondrogenic potential of human adipose derived stem cells (hASCs) makes them a possible source of seeding cells for cartilage tissue engineering. In this study, chondrogenic differentiation of hASCs induced by transduction with replication-deficient adenovirus carrying human transforming growth factor beta2 (Ad5-hTGF beta2) was demonstrated by RT-PCR, immunohistochemistry staining, biochemical and western blot analysis. To evaluate if the in vitro differentiated hASCs could keep their chondrocytic phenotype and produce neo-cartilage in vivo, predifferentiated hASCs were seeded in different scaffolds and implanted in subcutaneous pockets on the dorsum of nude mice. After 4 and 12 weeks culture in vivo, specimens were harvested and examined by histological and immunohistochemical analysis, cartilage-like tissue formation was only found in alginate gel and PLGA/alginate compound groups, in PLGA group, fibrous tissues and angiogenesis ingrowth were observed. These findings demonstrated that adenovirus-mediated hTGF beta2 gene transfer could induce hASCs into a chondrogenic lineage in vitro, however, this predifferentiation did not guarantee ectopic cartilage formation in vivo unless appropriate three-dimensional scaffolds were used as the cell carry vehicles.

Tissue engineered cartilage from hTGF beta2 transduced human adipose derived stem cells seeded in PLGA/alginate compound in vitro and in vivo.

Chondrogenic potential of human adipose derived stem cells (hASCs) makes them a possible source of seeding cells for cartilage tissue engineering. We aim to examine the chondrogenic differentiation of human transforming growth factor beta2 (hTGF beta2) transduced hASCs seeded in three-dimensional scaffold in vitro and in vivo. In this study, hASCs were isolated from human subcutaneous adipose tissue and transduced with a replication deficient adenovirus carrying hTGF beta2 (Ad5-hTGF beta2), and then the transduced cells were seeded and cultured in PLGA/alginate compounds. RT-PCR analysis revealed that Ad5-hTGF beta2 transduced hASCs produced aggrecan and collagen type II after 7-day induction in vitro and continued throughout the culture period; this was also demonstrated by the positive staining of Alcian blue and immunohistochemistry for collagen type II. For in vivo study, Ad5-hTGF beta2 transduced hASCs seeded in PLGA/alginate compounds were implanted in subcutaneous pockets of nude mice; after 12 weeks, the implants were harvested and examined by haematoxylin and eosin staining, AB-PAS staining, and immunohistochemical analysis, and the results demonstrated the formation of cartilage tissue. As a control, all these were not observed in the constructs with Ad5-EGFP transduced hASCs. In conclusion, our study demonstrates that adenovirus-mediated hTGF beta2 gene transfer is able to induce the hASCs into chondrogenic lineage both in vitro and in vivo. Ad5-hTGF beta2 transduced hASCs combined with three-dimensional PLGA/alginate compound may be a viable method in treating injuries of cartilage.

Neocartilage formation from predifferentiated human adipose derived stem cells in vivo.

AIM: To examine the chondrogenic potential of human adipose derived stem cells (hASC) induced by human transforming growth factor beta2 (hTGF beta2) in vitro, and to investigate if predifferentiated hASC can produce neocartilage in vivo. METHODS: hASC were isolated from subcutaneous adipose tissue and cultured in pellets with the addition of hTGF beta2. Chondrogenic differentiation was assayed by RT-PCR, Western blotting, toluidine blue staining, and immunohistochemistry staining for collagen type II. For the in vivo study, intact induced cell pellets or the released cells embedded in alginate gel with different concentrations were implanted subcutaneously in nude mice. Specimens were harvested at different time points and carried with histological and immunohistochemistry examination to evaluate the cartilage formation. RESULTS: RT-PCR analysis revealed that hASC produced aggrecan and collagen type II after 7 d of induction and continued throughout the culture period. This was also demonstrated by the Western blot analysis, positive staining of toluidine blue, and immunohistochemistry for collagen type II. After reseeding in the monolayer, the cells isolated from the pellets displayed a polygonal morphology compared with the primary spindle shape. hASC were released from the induced cell pellets when embedded in alginate gel (implanted cell concentration=5X10(6) /mL or higher). They produced neocartilage after 12 weeks in vivo culture; however, intact induced cell pellets implanted subcutaneously rapidly lost their differentiated phenotype. CONCLUSION: Chondrogenesis of hASC in vitro can be induced by combining pellet culture and hTGF beta2 treatment. Predifferentiated hASC embedded in alginate gel have the ability of producing neocartilage in vivo.

Treatment of rabbit growth plate injuries with an autologous tissue-engineered composite. An experimental study.

Tissue engineering has become a promising way of treating growth plate injuries. In this study, we attempted investigating the role of the autologous tissue-engineered composite in the treatment of rabbit growth plate injuries. Growth plate chondrocytes from iliac crest epiphyseal cartilage of immature New Zealand rabbits were obtained by dissection and sequential digestion with 0.2% collagenase (type II). After proliferating in monolayer culture in vitro for 3 weeks, the cells were harvested and seeded onto the demineralized bone matrix (DBM) scaffold to construct the composite. The autologous tissue-engineered composites were finally implanted into the proximal right tibia defects of the growth plate created in 12 rabbits (group A underwent the operation after obtaining chondrocytes 3 weeks beforehand), another 12 rabbits were implanted with only the DBM scaffold (group B), and the defects in group C (12 rabbits) were not implanted. The left tibias of all animals were left undone as the normal control. Two weeks after the operation, severe shortness and angulation deformity of the right tibia evaluated by X-ray were gradually observed in groups B and C. However, there were no obvious changes in group A and there were significant differences between group A and groups B and C (p < 0.05) at the 4-, 8-, and 16-weeks time points. 16 weeks after operation, histological examination revealed that the defects of the right tibias in group A had restored to almost the normal columnar structure of the growth plate. The results demonstrate that tissue-engineered composite established by combination of autologous growth plate chondrocytes and DBM can prevent the formation of a bone bridge and restore the growth of damaged growth plate.