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(Circulation. 2003;108:II-219.)
© 2003 American Heart Association, Inc.

Cardiac Transplantation and Surgery for Congestive Heart Failure

Improved Left Ventricular Aneurysm Repair With Bioengineered Vascular Smooth Muscle Grafts

Keiji Matsubayashi, MD^*; Paul W.M. Fedak, MD; Donald A.G. Mickle, MD; Richard D. Weisel, MD; Tsukasa Ozawa, MD, PhD; Ren-Ke Li, MD, PhD

From the Department of Surgery, Division of Cardiac Surgery, Toronto General Research Institute, Toronto General Hospital, University of Toronto, Toronto, Ontario, Canada; *Department of Surgery, Division of Cardiovascular Surgery, Shiga University of Medical Science, Shiga, Japan.

Correspondence to Ren-Ke Li, MD, PhD, Toronto General Hospital, NU 1-11.5A, 200 Elizabeth Street, Toronto, Ontario, M5G 2C4, Canada. Phone: 416-340-3361; Fax: 416-340-4806; E-mail: RenKeLi{at}uhnres.utoronto.ca

Background— Recurrent ventricular dilatation can occur after surgical repair of a left ventricular (LV) aneurysm. Use of an autologous bioengineered muscle graft to replace resected scar tissue may prevent recurrent dilatation and improve cardiac function.

Methods— Vascular smooth muscle cells (SMCs, 5x10⁶ cells) from rat aortas were seeded onto synthetic PCLA (sponge polymer of -caprolactone-co-L-lactide reinforced with knitted poly-L-lactide fabric) patches and cultured for 2 weeks to allow tissue formation. Syngenic rats underwent proximal left coronary artery ligation to create a transmural myocardial scar. Four weeks after coronary ligation, cell-seeded patches (n=15) or unseeded patches (n=12) were used for a modified endoventricular circular patch plasty (EVCPP) repair of the infarct area. Ligated controls (n=14) and nonligated normal rats (n=10) had sham surgeries without EVCPP. Cardiac function was assessed by echocardiography and isolated Langendorff heart perfusion. Graft histology and morphology was also assessed.

Results— After 8 weeks in vivo, seeded patches were thicker (P<0.05) and smaller in area (P<0.003) than unseeded patches. Only seeded patches had prominent elastic tissue formation (P<0.001) in association with SMCs. LV systolic function by echocardiography was improved in the seeded group compared with both unseeded (P<0.002) and control groups (P<0.0001). LV volumes in both patch repair groups were comparable but were significantly smaller (P<0.05) than controls. LV distensibility tended toward improvement in the seeded group as compared with unseeded hearts, but the difference did not achieve statistical significance (P=0.06).

Conclusions— Surgical repair with muscle-cell seeded grafts reduced abnormal chamber distensibility and improved LV function after myocardial infarction as compared with unseeded grafts. Bioengineered muscle grafts may be superior to synthetic materials for the surgical repair of LV scar.

Key Words: left ventricular aneurysm • remodeling surgery • tissue engineering • smooth muscle cells • biomaterials