title: In vitro preprogramming of marrow stromal cells for myocardial regeneration.
abstract: BACKGROUND
  We have previously reported that marrow stromal stem cells (MSCs), when implanted into myocardium, can undergo milieu-dependent differentiation to express phenotypes similar to the cells in the immediate microenvironment. We tested the hypothesis that by in vitro preprogramming of MSCs, we may be able to guide their differentiation to express a therapeutically desirable phenotype that is different from those in their microenvironment.
  
  
  METHODS
  MSCs were isolated from isogenic Lewis rats, culture expanded, and labeled with beta-gal using retrovirus carrying the lac-Z gene. A subset of the transfected MSCs was then treated with 5-aza-2'deoxycytidine (5-aza). Three weeks after the left ventricles were cryoinjured, either 5-aza-pretreated (n = 10) or untreated (n = 8) MSCs were injected into the myocardial scar. The hearts were harvested 4 to 8 weeks later and stained immunohistochemically for phenotypic markers.
  
  
  RESULTS
  The labeled MSCs within the scars that were 5-aza pretreated appeared to be morphologically distinct from the untreated ones. The treated cells (8/10 rats) appeared more myotube-like, with elongated nuclei, linearly aligned with one another, and stained positive for the cardiomyocyte-specific marker troponin I-C. Untreated MSCs (5/8 rats), in contrast, were poorly differentiated, and some appeared to express other phenotypes seen in the scar tissue.
  
  
  CONCLUSIONS
  Our findings indicate that in cellular cardiomyoplasty using MSCs, one may select different strategies to achieve specific therapeutic goals. By milieu-dependent differentiation, unmodified MSCs may augment myocardial angiogenesis and myogenesis, whereas converting scar into myogenic tissue may be facilitated by preprogramming of MSCs before implantation.
authors.affiliation: Division of Cardiac Surgery, McGill University Health Center, Montreal, Quebec, Canada.
authors.forename: Bindu
authors.initials: B
authors.lastname: Bittira
authors.forename: Jin-Qiang
authors.initials: JQ
authors.lastname: Kuang
authors.forename: Abdulaziz
authors.initials: A
authors.lastname: Al-Khaldi
authors.forename: Dominique
authors.initials: D
authors.lastname: Shum-Tim
authors.forename: Ray C J
authors.initials: RC
authors.lastname: Chiu
mesh_terms: D000818:Animals; D001854:Bone Marrow Cells / Q000502:physiology*; D016026:Bone Marrow Transplantation; D002454:Cell Differentiation / Q000502:physiology; D003841:Deoxycytidine / Q000494:pharmacology; D006321:Heart / Q000502:physiology*; D007150:Immunohistochemistry; D066298:In Vitro Techniques; D008297:Male; D051381:Rats; D011917:Rats, Inbred Lew; D012038:Regeneration / Q000502:physiology*; D017154:Stromal Cells / Q000502:physiology / Q000637:transplantation; D014162:Transfection; D014336:Troponin / Q000032:analysis; D001616:beta-Galactosidase / Q000032:analysis
chemical_list: D014336:Troponin; D003841:Deoxycytidine; D001616:beta-Galactosidase