Assessment of selective homing and contribution to vessel formation of cryopreserved peripherally injected bone marrow mononuclear cells following experimental myocardial damage

In view of a potential clinical use we aimed this study to assess the selective homing to the injured myocardium and the definitive fate of peripherally injected labeled and previously cryopreserved Bone Marrow Mononuclear cells. (BMMNCs)The myocardial damage (cryoinjury) was produced in 50 rats (45 treated, 14 controls). From 51 donor rats 4,4 x 10^9 BMMNCs were isolated and cryopreserved (slow-cooling protocols); the number of CD34+ and the viability of pooled cells was assessed by flow-cytometry analysis before and after cryopreservation and simulated delivery through a 23 G needle: Seven days injury, BMMNCs were thawed, labeled with PKH26 dye and peripherally injected (20 x 10^6 cells in 500 micronlitri) in recipeint rats. Two weeks after experimental injury, the heart lungs, liver, kidney, spleen PKH26+ cells were found only in the infarceted areas of all animals; treated rats showed a significantly higher number of these structures if compared with untreated. Morphological ultra-structural examination of infarcted areas confirmed in treated rats the presence of early-stage PKH26+ vascular structures derived from injected BMMNCs. The estimated mean CD34+ cells loss due to the cryopreservation procedure and to the system of delivery was 0.24% and 0.1%, espectively, confirming the feasibility of the prcedure. This study supports the possible therapeutic use of cryopreserved peripherally injecetd BMMNCs as a source of CD34+ independet vascular structures following myocardial damage