[Effects of mannose-6-phosphate on transforming growth factor beta and transforming growth factor beta receptor expression of flexor tendon cells]

Abstract

Objective: By culturing tendon sheath fibroblasts, epitenon tenocytes and endotenon tenocytes of rabbits' tendon in vitro, to study the effects of mannose-6-phosphate on transforming growth factor beta (TGF-beta) peptide and receptor expression, and to provide the experimental basis for preventing the tendon healing adhesion by mannose-6-phosphate.

Methods: Eight adult New Zealand white rabbits, regardless of their gender and weighing 4.0-4.5 kg, were selected. Tendon sheath fibroblasts, epitenon tenocytes, and endotenon tenocytes were isolated from rabbit flexor tendon and cultured separately. All 3 cells were divided into 2 groups at random after cells were adjusted to a concentration of 4 x 10(4) per well and 1 x 10(4)/mL. The first was the control group without supplementation. The experimental group was supplemented with mannose-6-phosphate. The expressions of TGF-beta and TGF-beta receptor were quantified with enzyme-linked immunosorbent assay. The expression of TGF-beta1 mRNA was also assessed with in situ hybridization and the expression of TGF-beta1 was assessed with immunohistochemistry.

Results: The expressions of TGF-beta and TGF-beta receptor in experimental group were significantly lower than that in control group (P < 0.05). The expression levels of TGF-beta1 and TGF-beta2 decreased in descending order of tendon sheath fibroblasts (36.1%, 37.9%), epitenon tenocytes (31.0%, 32.1%), and endotenon tenocytes (31.2%, 27.0%). The expression levels of TGF-beta3 decreased in descending order of endotenon tenocytes (42.5%), tendon sheath fibroblasts (41.2%), and epitenon tenocytes (33.3%). The expression levels of TGF-beta receptor 1 and TGF-beta receptor 2 decreased in descending order of epitenon tenocytes (29.9%, 26.2%), endotenon tenocytes (27.8%, 23.5%), and tendon sheath fibroblasts (23.1%, 20.0%). The expression levels of TGF-beta receptor 3 decreased in descending order of endotenon tenocytes (26.1%), epitenon tenocytes (19.2%), and tendon sheath fibroblasts (15.8%). In experimental group, the positive expression of TGF-beta1 mRNA and the expression level of intracellular TGF-beta1 mRNA in all 3 tendon cells were significantly lower than those in the control group (P < 0.05). Immunohistochemical staining showed the expressions of TGF-beta1 in all 3 tendon cells were significantly lower in the experimental group than in the control group.

Conclusion: Mannose-6-phosphate can significantly decrease the expressions of TGF-beta peptide, TGF-beta receptor, and TGF-beta1 mRNA. Modulation of mannose-6-phosphate levels may provide a mean of modulating the effects of TGF-beta on adhesion formation in flexor tendon wound healing.