TrkA regulates the regenerative capacity of bone marrow stromal stem cells in nerve grafts

Mei-Ge Zheng; Wen-Yuan Sui; Zhen-Dan He; Yan Liu; Yu-Lin Huang; Shu-Hua Mu; Xin-Zhong Xu; Ji-Sen Zhang; Jun-Le Qu; Jian Zhang; Dong Wang

doi:10.4103/1673-5374.257540

TrkA regulates the regenerative capacity of bone marrow stromal stem cells in nerve grafts

Neural Regen Res. 2019 Oct;14(10):1765-1771. doi: 10.4103/1673-5374.257540.

Authors

Mei-Ge Zheng¹, Wen-Yuan Sui², Zhen-Dan He³, Yan Liu⁴, Yu-Lin Huang², Shu-Hua Mu⁵, Xin-Zhong Xu⁶, Ji-Sen Zhang⁶, Jun-Le Qu⁷, Jian Zhang³, Dong Wang²

Affiliations

¹ Department of Orthopedics, The Seventh Hospital of Sun Yat-sen University, Shenzhen, Guangdong Province, China; Department of Orthopedics, The Second Hospital of Anhui Medical University, Hefei, Anhui Province, China.
² Department of Orthopedics, The Seventh Hospital of Sun Yat-sen University, Shenzhen, Guangdong Province, China.
³ School of Medicine, Shenzhen University, Shenzhen, Guangdong Province, China.
⁴ Department of Scientific Research, The Seventh Hospital of Sun Yat-sen University, Shenzhen, Guangdong Province, China.
⁵ Psychology & Social College of Shenzhen University, Shenzhen, Guangdong Province, China.
⁶ Department of Orthopedics, The Second Hospital of Anhui Medical University, Hefei, Anhui Province, China.
⁷ Key Laboratory of Optoelectronic Devices and Systems of Ministry of Education and Guangdong Province, College of Optoelectronic Engineering, Shenzhen University, Shenzhen, Guangdong Province, China.

Abstract

We previously demonstrated that overexpression of tropomyosin receptor kinase A (TrkA) promotes the survival and Schwann cell-like differentiation of bone marrow stromal stem cells in nerve grafts, thereby enhancing the regeneration and functional recovery of the peripheral nerve. In the present study, we investigated the molecular mechanisms underlying the neuroprotective effects of TrkA in bone marrow stromal stem cells seeded into nerve grafts. Bone marrow stromal stem cells from Sprague-Dawley rats were infected with recombinant lentivirus vector expressing rat TrkA, TrkA-shRNA or the respective control. The cells were then seeded into allogeneic rat acellular nerve allografts for bridging a 1-cm right sciatic nerve defect. Then, 8 weeks after surgery, hematoxylin and eosin staining showed that compared with the control groups, the cells and fibers in the TrkA overexpressing group were more densely and uniformly arranged, whereas they were relatively sparse and arranged in a disordered manner in the TrkA-shRNA group. Western blot assay showed that compared with the control groups, the TrkA overexpressing group had higher expression of the myelin marker, myelin basic protein and the axonal marker neurofilament 200. The TrkA overexpressing group also had higher levels of various signaling molecules, including TrkA, pTrkA (Tyr490), extracellular signal-regulated kinases 1/2 (Erk1/2), pErk1/2 (Thr202/Tyr204), and the anti-apoptotic proteins Bcl-2 and Bcl-xL. In contrast, these proteins were downregulated, while the pro-apoptotic factors Bax and Bad were upregulated, in the TrkA-shRNA group. The levels of the TrkA effectors Akt and pAkt (Ser473) were not different among the groups. These results suggest that TrkA enhances the survival and regenerative capacity of bone marrow stromal stem cells through upregulation of the Erk/Bcl-2 pathway. All procedures were approved by the Animal Ethical and Welfare Committee of Shenzhen University, China in December 2014 (approval No. AEWC-2014-001219).

Keywords: Bcl-2; bone marrow stromal stem cells; extracellular signal-regulated protein kinases 1/2; lentiviral vector; nerve grafts; nerve regeneration; neural regeneration; peripheral nerve regeneration; shRNA; survival; tropomyosin receptor kinase A receptor.