Phenotypic changes in cultured smooth muscle cells: limitation or opportunity for tissue engineering of hollow organs?

Smooth muscle cells (SMCs) are typically used as a cell source for the reconstruction of hollow organs by conventional tissue engineering techniques. However, the necessity and advantage for the use of tissue specific SMCs is unknown. The present study investigated the phenotypic changes that occur following isolation and in vitro expansion of rat SMC populations isolated from three different tissues: the aorta, esophagus, and urinary bladder. rSMCs were isolated by enzymatic dispersion and expanded by conventional cell culture techniques yielding microscopically homogeneous populations. SMC phenotypes were monitored according to their expression of marker proteins during the first two passages. Two of the three SMC populations (rSMC-a and rSMC-e) showed a marked change in their marker protein profiles during the first two passages which resulted in a homogenous phenotype that was neither fully contractile nor fully synthetic. SMCs from the urinary bladder did not show such a shift. Differences between the three rSMC populations were observed with regard to proliferative activity and gene expression patterns suggesting the retention of some tissue-specific cell characteristics. In summary, phenotypic changes in SMCs occur as a result of conventional cell isolation and expansion techniques, thus questioning the necessity of a tissue specific cell source for regenerative medicine applications.

平滑肌细胞（SMCs）通常被用作通过传统组织工程技术重建中空器官的细胞来源。然而，使用组织特异性平滑肌细胞的必要性和优势尚不明确。本研究调查了从三种不同组织（主动脉、食管和膀胱）分离的大鼠平滑肌细胞群在分离和体外扩增后发生的表型变化。通过酶解分散法分离大鼠平滑肌细胞，并通过常规细胞培养技术进行扩增，得到显微镜下均一的细胞群。在前两代培养过程中，根据标记蛋白的表达来监测平滑肌细胞的表型。三种平滑肌细胞群中的两种（rSMC - a和rSMC - e）在前两代培养过程中其标记蛋白图谱发生了显著变化，导致形成一种既不完全收缩也不完全合成的均一表型。来自膀胱的平滑肌细胞没有出现这种转变。在增殖活性和基因表达模式方面观察到三种大鼠平滑肌细胞群之间存在差异，这表明保留了一些组织特异性细胞特征。总之，由于常规的细胞分离和扩增技术，平滑肌细胞会发生表型变化，因此对再生医学应用中组织特异性细胞来源的必要性提出了质疑。