应用脂肪干细胞构建组织工程化小口径血管平滑肌层的实验研究

Experimental Study on Tissue Engineered Small-Diameter Blood Vessel Walls Using Adipose Derived Stem Cells

目的探索利用脂肪干细胞在生物反应器内构建组织工程血管平滑肌层的可行性。方法用抽吸的脂肪获取脂肪干细胞,在生长因子TGF-β1和BMP4作用下诱导成平滑肌细胞,然后将诱导的平滑肌细胞接种于PGA上,将细胞-材料复合物置于生物反应器内进行培养,在模拟胚胎发育血流动力学的刺激下(搏动频率:75次/分;扩展量<5%),构建小口径的血管平滑肌组织。培养8周后,取材行组织学和生物力学检测并与正常血管对比。结果脂肪干细胞在TGF-β1和BMP4的诱导下,细胞呈现平滑肌细胞特有的"波峰-波谷"样生长特点,并表达平滑肌细胞的特异性标记物α-SMA、SM22α、calponin和SM-MHC;反应器内培养8周后,构建的管状组织胶原分泌旺盛,具有一定的力学强度和弹性。结论利用脂肪干细胞可在体外生物反应器内构建组织工程化小口径血管平滑肌层,为临床上小血管病变的修复提供了一种新的可能的途径。

Objective To investigate the feasibility of constructing tissue engineered blood vessel walls in bioreactor using adipose derived stem cells. Methods Adipose derived stem cells （ADSCs） were obtained from fresh human lipoaspirates, and under the induction of TGF-β1 and BMP4, hADSCs were differentiated into smooth muscle cells, and then the differentiated hADSCs were collected and seeded onto PGA mesh to form cell-PGA constructs. Thereafter, the cell/PGA constructs were cultivated in a bioreactor with the pulsatile radial stress （pulse rate： 75/min, radical distension〈5%） for 8 weeks. New small diameter blood vessel walls was formed, the constructs were examined histologically and biomeehanically and compared with normal blood vessels. Results With induction of TGF-βand BMP4 together, hADSCs acquired a SMC morphology, and grew in a ＂hill and valley＂ pattern similar to what was observed in primary isolated hUASMCs, with the expression of smooth muscle-specific contractile proteins including α-SMA, SM22α, calponiu, and SM-MHC. An elastic small diameter vessel wall （4 mm in diameter） with improved biomechanical strength and well-organized collagenous fibers were engineered by in vitro culture of SMC-differentiated hADSCs on the PGA scaffold in a blood vessel bioreactor. Conclusion hADSCs can serve as a new cell source for SMCs in blood vessel engineering, and an elastic small diameter vessel wall could be engineered in a bioreactor. It is a promising candidate for treating cardiovascular diseases and for blood vessel engineering purposes.