Fibroblast sheets co-cultured with endothelial progenitor cells improvecardiac function of infarcted hearts

Authors:
Hiroshi Kobayashi, MD · Tatsuya Shimizu, MD, PhD
Masayuki Yamato, PhD · Kayoko Tono, MS
Haruchika Masuda, MD, PhD
Takayuki Asahara, MD, PhD
Hiroshi Kasanuki,MD, PhD · Teruo Okano, PhD

J Artif Organs (2008) 11:141–147

The study was done in an effort to improve existing therapies for better cardiac function post heart attack or other related injuries (post attack, usually ventricular function declines). Namely, the focus has been on treatments involving regenerative medicine. Echoing other contributors of the blog, heart problems remains the leading cause of death and a main concern in the present day population. With new and better ways to treat injuries, we can prolong lives and improve life quality post a (serious) heart injury.

Brief Materials Used:
Animal model used: male athymic rats (8-10 weeks old); induced myocardial infarction by ligating the left anterior descending coronary artery so that blood flow ceases. Guinea pigs are another possible model that could have been used. Their hearts are similar to humans (with electrical conduction system and similar muscle contraction system) and bigger than rats or mice. (ref: http://scienceandresearch.homeoffice.gov.uk/animal-research/publications-and-reference/001-abstracts/abstracts2-2006/04september-2006/373?view=Html). The endothelial progenitor cell (EPC) cultures were made from peripheral blood mononuclear cells from Sprague-Dawley rats; fibroblast sheets were cultured from abdominal skin samples from Wistar rats. Refer to article for details of the cell density, time of culture, temperatures, etc.

Experiment:
All rats underwent the induced infarction. Then they were randomly put into four equal sized (n=5) groups: one control who received transplant operation but no transplant (C group), one group received only EPC (E group), one group received only triple-layer fibroblast sheets (F group), and last group received the sandwich-like construct of sheets+EPC (E+F group).

Echocardiographies before transplantation and then weekly for a month were used to measure rat cardiac function. And the animals were sacrificed at the end of the period for histological analyses. Statistical analyses proceeded to evaluate the data. Examples of variables investigated include left ventricular dimensions/wall thickness, quantity of connective tissue via staining. Left ventricular performance (measured by echocardiograph) had significant improvement one week after transplation (and in weeks 2, 3, 4) in the E+F group compared to C group. The other two groups also showed better results than control but not significantly different compared to E+F group. Vascularization in the E+F group was better than E and C group. The vessel walls included both EPC and fibroblasts for the E+F group, suggesting higher effectiveness in transplantation of EPC+Fibroblasts than either two alone. The combination of EPC and fibroblast sheet allows for better adhesion (single cells can and do wash out easily), and accelerate vascularization (with combination of EPC and growth factors embedded between the sheets). Previous studies with fibroblast sheet alone or endothelial cells alone have shown that combination therapy is, in fact, an improvement.

Although the data gathered for this particular paper doesn't show significant improvements from the combination therapy compared to the individualized therapies, the authors referred to results from many other similar and applicable previous experiments, justifying further investigation (using larger animal models, optimizing culturing period and transplant timing, larger sample size, perhaps older animals, etc.). The variables they measured and calculated correlated with cardiac functionalities to address the problem at hand.