ABSTRACT
Wound debridement for the removal of necrotic tissue is a crucial step in wound management. Enzymatic wound debridement is one example of a method currently used that removes necrotic tissue with proteases and offers selectivity without affecting healthy adjacent tissue. Proteolytic enzymes for wound debndement are commercially available as ointments. The authors previously proposed and demon- strated feasibility on small lab animals-an alternative mode of deliv- ery of proteolytic enzymes for wound debridement with continuous streaming of protease solutions. The present study describes the impact of streaming of papain solut ions, fort ified by the incorporation of hypertonic agents, onto an experimental larger chronic wound model in pigs. Debridement of approximately half of the necrotic tis- sue mass was achieved within 6 to 11 h of streaming of papain solu- tions onto these experimental wounds. No adverse effects or notice- able morphological changes to the wound surface or its immediate surroundings were noted, indicating enzyme selectivity and preference for attacking necrotic tissue. The mechanism of enzymatic attack on the necrotic tissue is also discussed. In the control group, streaming of the basic solution formula (devoid of papain) was performed-no debridement of necrotic tissue was noticed in this case. The results indicate that the streaming delivery mode for enzymatic debridement is a highly effective tool designed to be completed in a few sessions. thus paving the way for extension of its application in clinical trials on humans.
ABSTRACT
OBJECTIVE: To evaluate whether satellite cells injected into infarct areas in rabbits remain viable during 6 weeks follow-up and can improve cardiac function as assessed by echocardiography. METHODS: Myocardial infarction was induced in 16 New Zealand white rabbits, by ligation of the marginalis sinistra artery. Tissue from gluteus muscle biopsies was dissected into small pieces and cultured. Within 2-3 weeks the cells were expanded by 2-3 orders of magnitude and were fluorescent labeled. Single cell pellets for resuspension at >10(6)/1 ml were directly injected into the infarct areas in 8 rabbits. In 8 additional rabbits, 1 ml saline was injected (control). Regional left ventricular function was assessed weekly by 2-D echocardiography until animals were sacrificed. Analysis was performed blind and independently by two experienced echocardiographers, based on the American Society of Echocardiography scheme. RESULTS AND DISCUSSION: Six treated and five control rabbits completed the study. One week after the artery occlusion, left ventricular function scoring did not differ between groups, mean 8.7+/-1.6 vs 8.3+/-1.9 (P=0.74). At 6 weeks post-injection, echocardiographic score was significantly better in the treated group, mean 2.6+/-0.9 vs 6.9+/-2.1 (P=0.002). The treated group showed significant gradual segmental improvement between the first week up to week 6. After sacrifice, macro and microscopic transmural areas showed typical changes of myocardial infarction. Histochemical staining identified viable grafted cells in high density 6 weeks post-transplantation in all grafted hearts. CONCLUSION: Autologous satellite cells (skeletal myofiber), can be successfully grafted into rabbit hearts following myocardial infarction and may induce improved regional left ventricular function.
