Histological study on the effect of transplanted human umbilical cord blood CD34+ stem cells on albino rats subjected to myocardial infarction

Abstract

Background: Heart failure is a significant burden to health care systems in the world. One of its major causes is myocardial infarction (MI). Recent developments in stem cells may offer ways to manage heart failure by replacing damaged cardiac muscle with healthy tissue. This study aimed at examining the regenerative effect of intravenously transplanted human umbilical cord blood CD34+ stem cell in a rat model of acute MI.
Methods: Forty adult female rats were equally randomized into 5 groups. Groups I and II received saline alone or saline followed by isolation buffer respectively to serve as control groups. The other 3 groups were subjected to induction of acute MI using subcutaneous injection of isoprenaline hydrochloride. In groups III and IV, animals were sacrificed after one week and four weeks respectively. One week after induction of MI, animals in group V received intravenous injection of 4 x 10⁶ CD34+ stem cells separated from the human umbilical cord blood of male fetuses, and were sacrificed after 3 weeks from cell injection. At the end of the experiment, heart tissue was processed for both light and electron microscopic histological studies, and for PCR analysis of the male-specific SRY gene.
Results: Light microscopic results of group III revealed increased diameter and necrosis of cardiomyocytes, decreased cross-striations, vascular congestion and mononuclear cellular infiltration. Group IV revealed multiple extensive fibrotic areas. Group V revealed smaller fibrotic areas compared to Group IV. Ultrastructural results confirmed findings of the light microscope. PCR analysis revealed that 63% of heart samples were positive for the presence of SRY gene.
Conclusion: CD34+ stem cells can transdifferentiate into cardiomyocyte and regenerate the injured heart subjected to MI.

Keywords: HUCB, CD34+ stem cells, myocardial infarction, transdifferentiation