Effects of mesenchymal stem cells transplantation on the apoptosis after rabbit intervertebral disc degeneration

Abstract

Objective To investigate the effects of the mesenchymal stem cells (MSCs) transplantation on the apoptosis of nucleus pulposus cells after rabbit intervertebral disc degeneration. Methods New Zealand white rabbits were used to stimulate allograft. Harvested rabbit MSCs and fibroblasts were cultured , proliferated and labeled in vitro. At the same time, degenerated intervertebral disc models were set up using 21-gauge needle to puncture the annulus. Four weeks later, 2 X 106 MSCs and fibroblasts were injected into the respective disc segments. After 1,2,4 and 8 weeks, specimens from degenerated models were obtained in order. The number of apoptotic nucleus pulposus cells and the expression of Caspase-3 were detected under laser scanning confocal microscopy in every disc from the experimental group and the control groups of the rabbits. The bcl-2 and bax mRNA expression of all discs was assayed by real time reverse transcription-polymerase chain reaction (RT-PCR). Results The transmission electron microscopy revealed that part of the nucleus pulposus cells became apoptosis in the initial stage in ultramicrostructure. Apoptosis rate was (16.75 ±2. 14)% and (31. 87 ±4. 16)% in the experimental group and the degenerated group, as well as Caspase-3 expression ratio was (20. 34 ± 1. 03)% and (31. 50 ±3. 78)% respectively , demonstrating that MSCs could relieve apoptosis after rabbit intervertebral disc degeneration. The levels of bcl-2 mRNA expression in experimental group were higher than in the degenerated group (P<0.05). Conclusion Apoptosis is involved in the development of intervertebral disc degeneration. MSCs transplantation can increase the expression of bcl-2 mRNA in the nucleus pulposus and relieve apoptosis after rabbit intervertebral disc degeneration. Key words: MSCs; Intervertebral disc degeneration; Apoptosis; Green fluorescent protein