Adipose-derived mesenchymal stem cells treated with growth differentiation factor-5 express tendon-specific markers.

OBJECTIVES: Adipose-derived mesenchymal stem cells (ADMSCs) are a unique population of stem cells with therapeutic potential in the treatment of connective tissue injuries. Growth differentiation factor-5 (GDF)-5 is known to play a role in tendon repair and maintenance. The aim of this study was to investigate the effects of GDF-5 on proliferation and tendonogenic gene expression of rat ADMSCs. METHODS: ADMSCs were treated in culture with different concentrations of GDF-5 (0-1000 ng/mL) for 12 days. Biochemical, temporal, and concentration kinetic studies were done. Extracellular matrix (ECM) synthesis, tendonogenic differentiation, and matrix remodeling gene and protein expression were analyzed. RESULTS: GDF-5 led to increased ADMSC proliferation in a dose- and time-dependent manner. ADMSCs demonstrated enhanced ECM (collagen type I, decorin, and aggrecan) and tendonogenic marker (scleraxis, tenomodulin, and tenascin-C) gene expression with 100 ng/mL of GDF-5 (p < 0.05). ECM and tendon-specific markers showed time-dependent increases at various time points (p < 0.05), although decorin decreased at day 9 (p < 0.05). GDF-5 did alter expression of matrix remodeling genes, with no specific trends observed. Western blot analysis confirmed dose- and time-dependent increases in protein expression of tenomodulin, tenascin-C, Smad-8, and matrix metalloproteinase-13. CONCLUSION: In vitro GDF-5 treatment can induce cellular events leading to the tendonogenic differentiation of ADMSCs. The use of combined GDF-5 and ADMSCs tissue-engineered therapies may have a role in the future of tendon repair.

Minimization of genetic distances by the consensus, ancestral, and center-of-tree (COT) sequences for HIV-1 variants within an infected individual and the design of reagents to test immune reactivity.

Eliciting maximal immune responses to highly divergent viruses is a challenge and a focus in AIDS vaccine development. Another challenge is to identify the immune correlates of protective immunity. Recent AIDS vaccine design approaches attempt to use reconstructed centralized viral sequences that minimize genetic differences to circulating viruses. Using these approaches, we derive and analyze consensus (CON), ancestral (ANC), and center-of-tree (COT) sequences to represent intra-individual HIV-1 env variants encoding a range of diversities and phylogenetic structures. Each reconstructed sequence significantly minimized genetic distances to extant sequences throughout the first 5 years of infection of an individual. Interestingly, ANC sequences diverged and were not significantly better than extant sequences in minimizing genetic distances at later stages of infection and disease, likely due to the development of a substantially asymmetric phylogeny. COT or CON sequences derived from autologous virus samplings may be useful for increasing the sensitivity of assessments of immune reactivity against HIV.