Polypropylene suture

The female Lewis rats selected were between 200–250 g in weight (Charles River Laboratories, Senneville, Canada). All animal studies were performed in accordance with the guidelines set forth by the Canadian Council on Animal Care and were approved by the institutional ethics committee.
The rats were anesthetized, intubated, and mechanically ventilated at 85 breaths/minute. The left coronary artery was accessed via a left thoracotomy through the fourth intercostal space and permanently ligated 2 mm from its origin with a 7/0 polypropylene suture(Ethicon Inc, Somerville, NJ). The ischemic myocardial segment rapidly became identifiable by observing pallor and akinesia corresponding to the distribution area of the left coronary artery. Fifteen minutes after ligation of the artery, 3 equal peri-infarct intramyocardial injections, totaling 500 μL, of the previously harvested MSC or HiPSC culture media or normal saline were completed using a 27-gauge needle. The experimented animals survived up to 8 weeks for analysis. The rats were randomized into three groups: (i) non-treated group (n = 10, normal saline), (ii) treatment group HiPSC (n = 10, HiPSC secretome), (iii) treatment group hMSC (n = 10, hMSC secretome). All groups had coronary ligation and injection of treatment into the peri-infarct area.

Animals were anesthetized with inhalational isoflurane in 100% O₂ (5.0% induction; 2.5% maintenance). Endotracheal intubation was performed and the animals ventilated with positive-pressure ventilation. A left lateral thoracotomy was performed. The pericardial sac was identified and a small portion opened sharply exposing the left ventricle at the intended LAD ligation site. For animals that underwent MI, the LAD was identified and ligated with a 7–0 poly-propylene suture (Ethicon, Somerville, New Jersey) 1–2 mm from its origin.^{28 (link)} Visual confirmation of infarction was noted by edema and discoloration of the anterior LV wall. MSC or blank cell capsules were then deposited on a sterile surgical towel and then deposited in the pericardial space on the epicardial surface of the right and left ventricle with surgical forceps. For each animal 1.5mL of capsules were deposited. For animals in the MSC injection group, 0.2 cc (4×10⁶ cells per rat) were injected into the left ventricle myocardium in the infarct zone using a 27 gauge syringe. Cells were injected obliquely and the needle was not withdrawn for 10 seconds to minimize chance for cell leakage. The chest was then sutured closed in layers and the animals were extubated and allowed to recover.