An in vitro study of enhancing tendon-bone healing by human amniotic mesenchymal stem cells co-modified with hypoxia-inducible factor 1 alpha and Scleraxis gene / 中国组织工程研究

ABSTRACT

BACKGROUND: Tendon-to-bone healing is a complex and slow process, which often hinders the therapeutic outcomes. To enhance the tendon-to-bone healing, increasing cell bioactivity on the contact surface is a new strategy. Hypoxia-inducible factor 1α (HIF-1α) can induce the formation of blood vessel and bone tissue via many ways.However,it is unclear whether HIF-1α can strengthen differentiation of human amniotic mesenchymal stem cells (hAMSCs) induced by Scleraxis, a specific marker of tendon, and can be used in tendon and bone repair. OBJECTIVE: To investigate the ability of HIF-1α in enhancing Scleraxis to modify hAMSCs aiming to promote tendon-to-bone healing and its molecular mechanism. METHODS: Passage 3 hAMSCs were infected with AdHIF-1α, AdScx, AdGFP and AdHIF-1α+AdScx. The expressions of related genes of tendon, cartilage and bone tissue were detected at 3 and 7 days after infection. RESULTS AND CONCLUSION: Under the inverted phase contrast microscopy, the passage 3 hAMSCs were in spindle shape and presented with vortex-like adherent growth. Under the transmission electron microscopy, hAMSCs were in oval shape and had clear structure, with abundant endoplasmic reticulum and mitochondria. Fluorescence photographs were taken at 24 hours after adenovirus infection, showing about 50% red fluorescence expression in the AdHIF-1α group, while about 70% green fluorescence expression in the AdScx and AdGFP groups. Real time-PCR results showed that at 3 and 7 days after infection, the mRNA expressions of collagen type I, Fibronectin, RUNX2, VEGF and ALP in the AdHIF-1α+AdScx group, AdHIF-1α group and AdScx group were higher than those in the AdGFP group (P < 0.05); the mRNA expressions of collagen type I, Fibronectin, RUNX2, VEGF and ALP in the AdHIF-1α+AdScx group were significantly higher than those in the AdScx group (P < 0.05). Fluorescence immunohistochemistry results showed that the expression of collagen type I in the AdHIF-1α+AdScx group at 7 days after infection was higher than that at 3 days after infection. To conclude, HIF-1α can enhance the ability of Scleraxis to modify hAMSCs to promote tendon-to-bone healing by upregulating the expressions of molecular markers of tenocytes, chondrocytes and osteocytes.