Fetal Cardiac Cell Transplantation and Transcription Factor of the Heart

心脏细胞移植是治疗急性或慢性心力衰竭伴心肌明显丧失的一种潜在治疗方法。细胞移植到心脏成功的先决条件包括以下几点：1。移植心肌细胞和宿主心肌细胞之间形成新的功能性合胞体，2.移植细胞的数量大到足以改善心脏功能，以及3.移植物的长期存活率。将治疗基因转移到待移植的细胞中可能会解决这些障碍。开始，我们用编码β-半乳糖苷酶的重组质粒、逆转录病毒或腺病毒对转基因的胎儿心肌细胞进行细胞移植。我们发现腺病毒载体将报告基因转导到培养的心肌细胞中，没有任何损伤，并且移植的心肌细胞存活并表达β-gal 12周。宿主心肌细胞与移植细胞之间形成差距连接。另一方面，质粒载体的基因转移效率低，逆转录病毒介导的基因转移移植细胞不能在宿主心脏形成差距连接。基因转移的候选者是使心肌细胞增殖或使胚胎细胞分化为心肌细胞的基因。然而，其调控心肌细胞增殖和分化的机制尚不清楚。本研究检测了细胞周期相关基因Cyclin D1-3、Cyclin依赖性激酶抑制因子（p15、p16、p21、p27、p57）在含1%DMSO的α-MEM培养基中诱导P19 EC细胞向心肌细胞分化过程中的表达模式，结果提示Cyclin D2和p21可能在诱导P19 EC细胞向心肌细胞分化过程中起作用。p27和p57的功能可能是在向心肌细胞分化的过程中强烈抑制增殖。

Cardiac cell transplantation is the one potential treatment for acute or chronic heart failure with a significant loss of myocardium. Prerequisites for cellular transplantation to the heart to be successful include the followings : 1. formation of a new functional syncytium between grafted and host cardiomyocytes, 2. the number of grafted cells large enough to improve cardiac function, and 3. long-term graft survival. The transfer of a therapeutic gene into the cells to be grafted may possibly solve these obstacles. To begin with, we performed cell transplantation of the gene transferred fetal myocardial cells with recombinant plasmids, retroviruses, or adenoviruses coding beta-galactosidase. We found that adenovirus vector transduced the reporter gene into cultured cardiomyocytes without any damage, and that the grafted cardiac cells survived and expressed beta-gal for 12 weeks. The gap junctions were formed between the host cardiomyocytes and grafted cells. On the other hand, the plasmid vectors was little efficient for gene transfer, and the gene transferred grafted cells by the retroviruses could not form the gap junction in the host hearts. Candidates for gene transfer are the genes to make cardiomyocytes proliferate or to make embryonic cells differentiate into cardiomyocytes. However, the mechanisms of regulating the proliferation and differentiation of cardiomyocytes are unclear. We examined the expression patterns of cell cycle relating genes (Cyclin D1-3, Cyclin dependent kinase inhibitors (p15, p16, p21, p27, p57)) on P19 EC cells differentiating into cardiomyocytes under alpha MEM culture medium containing 1% DMSO.The results suggested that Cyclin D2 and p21 might play a role in induction of differentiation into cardiomyocytes. The function of p27 and p57 may be a strong inhibition of proliferation in process of differentiation into cardiomyocytes.