Tissue transglutaminase_variant 2-transduced mesenchymal stem cells and their chondrogenic potential.

As cartilage is incapable of self-healing upon severe degeneration because of the lack of blood vessels, cartilage tissue engineering is gaining importance in the treatment of cartilage defects. This study was designed to improve cartilage tissue regeneration by expressing tissue transglutaminase variant 2 (TGM2_v2) in mesenchymal stem cells (MSC) derived from bone marrow of rats. For this purpose, rat MSCs transduced with TGM2_v2 were grown and differentiated on three-dimensional polybutylene succinate (PBSu) and poly-l-lactide (PLLA) blend scaffolds. The transduced cells could not only successfully express the short form transglutaminase-2, but also deposited the protein onto the scaffolds. In addition, they could spontaneously produce cartilage-specific proteins without any chondrogenic induction, suggesting that TGM2_v2 expression provided the cells the ability of chondrogenic differentiation. PBSu:PLLA scaffolds loaded with TGM2_v2 expressing MSCs could be used in repair of articular cartilage defects.

Dual-Inhibition of mTOR and Bcl-2 Enhances the Anti-tumor Effect of Everolimus against Renal Cell Carcinoma In Vitro and In Vivo.

Renal cell carcinoma (RCC) is the predominant type of kidney cancer. Mammalian target of rapamycin (mTOR) inhibitor everolimus is currently used as a second-line therapy for sorafenib or sunitinib-refractory metastatic RCC patients. The clinical limitation confronted during everolimus therapy is the onset of drug resistance that decreases the efficacy of the drug. Elevated level of anti-apoptotic Bcl-2 protein is proposed to be an emerging feedback loop for the acquired drug-resistance in various cancer types. In this study, the Bcl-2 inhibitor ABT-737 was used in combination with everolimus to enhance its anti-tumor effectiveness in everolimus-resistant RCC cell lines. Everolimus and ABT-737 combination synergistically led to a decrease in the proliferation of primary site A-498 and metastatic site Caki-1 RCC cell lines, which was accompanied by a reduction in protein levels of cell cycle and mTOR pathway proteins. In both RCC cell lines, everolimus-ABT-737 combination not only induced apoptosis, caspase and PARP-1 cleavage but also a decrease in Bcl-2 protein levels in parallel with a concomitant increase in Bim and Noxa levels. In order to confirm our in vitro findings, we have generated everolimus-resistant RenCa cell line (RenCares) to establish a RCC mouse xenograft model. Animals co-treated with everolimus and ABT-737 exhibited a complete suppression of tumor growth without any notable toxicity. This study thus proposes the everolimus-ABT-737 combination as a novel therapeutic strategy for the treatment of RCC to overcome the current clinical problem of everolimus resistance.