Aesthetic and Plastic Surgery Institute (Gharibjanian, Chua, Dhar, Scholz)
Department of Otolaryngology/Head and Neck Surgery (Shibuya)
Aesthetic and Plastic Surgery Institute, University of California, Irvine, Orange, Calif. (Evans, Calvert)
Correspondence to Dr. Calvert, Department of Surgery, Veterans Affairs Hospital, 5901 East 7th Street, Long Beach, Calif. 90822, firstname.lastname@example.org
We thank Dr. Pereira and colleagues for their letter and very insightful comments. We agree that the cell adhesion to various polymer surfaces can be varied because of differential topographic surfaces and/or cytoskeletal stress, which in turn can lead to reduced cell adhesion and thus decreased osteogenesis. At the same time, it is important to mention that the initial adhesion of cells in our study to polymers was normalized, to avoid statistical bias. Furthermore, to avoid the bias of bone morphogenetic protein (BMP)-2 release occurring because of exposure to 6N sulfuric acid during covalent binding of BMP-2, we followed a process wherein the polymer was first treated with 6N sulfuric acid followed by BMP-2 binding.1 This technique more or less includes the effect of 6N sulfuric acid on polymer structure before BMP-2 binding and thus results in minimal interference on regulation and expression of genes involved in osteogenesis. We also want to mention that it is possible that acid hydrolysis, which is essential to the covalent binding process, can cause polycaprolactone degradation. Further studies could investigate the degradation rate of polycaprolactone and poly(lactic-co-glycolic acid) in association with acid concentration. Our experience has shown that 6N sulfuric acid provides optimal binding characteristics, but future adjustments could be tailored to differing applications. We completely agree that future studies incorporating these suggestions will further elucidate the nature and function of these polymers and their release kinetics.
Nareg A. Gharibjanian, M.S.
Walter C. Chua, M.D.
Sanjay Dhar, Ph.D.
Thomas Scholz, M.D.
Aesthetic and Plastic Surgery Institute
Terry Y. Shibuya, M.D.
Department of Otolaryngology/Head and Neck Surgery
Gregory R. D. Evans, M.D.
Jay W. Calvert, M.D.
Aesthetic and Plastic Surgery Institute
University of California, Irvine
1. Shibuya TY, Kim S, Nguyen K, et al. Covalent linking of proteins and cytokines to suture: Enhancing the immune response of head and neck cancer patients. Laryngoscope
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