Birla Ravi K, Dhawan Vikas, Dow Douglas E, Huang Yen-Chih, Brown David L
Section of Cardiac Surgery, University of Michigan, MSRB I, A510E, 1150 West Medical Center Drive, Ann Arbor, MI 48109, USA.
Biotechnol Lett. 2009 Feb;31(2):191-201. doi: 10.1007/s10529-008-9859-2. Epub 2008 Oct 15.
We have previously described a model to implant dissociated cells into a cylindrical, vascularized bed in vivo to promote the formation of functional cardiac muscle constructs. We now investigate the cellular organization and the ability of the constructs to generate intra-luminal pressure. Primary cardiac cells were isolated from hearts of 2-3 day old rats, suspended in fibrin gel and inserted into the lumen of silicone tubing. The silicone tubing was then implanted around the femoral vessels in the groin region of recipient animals. After 3 weeks, the constructs were harvested, placed in an in vitro bath and cannulated via the incorporated femoral artery with a pressure transducer for evaluation of intra-luminal pressure dynamics. Histological evaluation showed the presence of a concentric ring of cardiac cells surrounding the femoral vessels. There was also a significant amount of collagen present around cardiac cells. In addition, we observed a significant amount of neovascularization of the explanted constructs. Electron microscopy showed the presence of longitudinally aligned fibers with a large number of gap junctions. Upon electrical stimulation of a single pulse (7 V, 1.2 ms), the constructs generated an intra-luminal pressure of 1.19 +/- 0.45 mmHg (n = 6). In addition, we were able to electrically pace the constructs at frequencies of 0.5-5 Hz. A Starling behavior of the inverse relation between baseline pressure and twitch pressure was observed. Cardiac cells implanted for 3 weeks into the cylindrical vascularized bed formed a tissue construct that demonstrated many of the contractile properties and morphology expected of functioning cardiac tissues.
我们之前描述了一种模型，可将解离的细胞植入体内圆柱形的血管化床中，以促进功能性心肌构建体的形成。我们现在研究构建体的细胞组织以及产生腔内压力的能力。从2 - 3日龄大鼠的心脏中分离出原代心肌细胞，将其悬浮在纤维蛋白凝胶中，并插入硅胶管腔。然后将硅胶管植入受体动物腹股沟区域的股血管周围。3周后，收获构建体，置于体外浴槽中，并通过内置的股动脉用压力传感器插管，以评估腔内压力动态。组织学评估显示股血管周围存在一圈同心的心肌细胞。心肌细胞周围也存在大量胶原蛋白。此外，我们观察到移植的构建体有大量新生血管形成。电子显微镜显示存在纵向排列的纤维以及大量间隙连接。在单次脉冲（7 V，1.2 ms）电刺激下，构建体产生的腔内压力为1.19±0.45 mmHg（n = 6）。此外，我们能够以0.5 - 5 Hz的频率对构建体进行电起搏。观察到基线压力与收缩压呈反比的斯塔林行为。植入圆柱形血管化床3周的心肌细胞形成了一种组织构建体，其表现出许多功能正常的心脏组织所预期的收缩特性和形态。
