Alyssa R. Golas

Tissue engineering for plastic surgeons: a primer.

A central tenet of reconstructive surgery is the principle of “replacing like with like.” However, due to limitations in the availability of autologous tissue or because of the complications that may ensue from harvesting it, autologous reconstruction may be impractical to perform or too costly in terms of patient donor-site morbidity. The field of tissue engineering has long held promise to alleviate these shortcomings. Scaffolds are the structural building blocks of tissue-engineered constructs, akin to the extracellular matrix within native tissues. Commonly used scaffolds include allogenic or xenogenic decellularized tissue, synthetic or naturally derived hydrogels, and synthetic biodegradable nonhydrogel polymeric scaffolds. Embryonic, induced pluripotent, and mesenchymal stem cells also hold immense potential for regenerative purposes. Chemical signals including growth factors and cytokines may be harnessed to augment wound healing and tissue regeneration. Tissue engineering is already clinically prevalent in the fields of breast augmentation and reconstruction, skin substitutes, wound healing, auricular reconstruction, and bone, cartilage, and nerve grafting. Future directions for tissue engineering in plastic surgery include the development of prevascularized constructs and rationally designed scaffolds, the use of stem cells to regenerate organs and tissues, and gene therapy.

Reduction of suture associated inflammation after 28 days using novel biocompatible pseudoprotein poly(ester amide) biomaterials

Sutures elicit an inflammatory response, which may impede the healing process and result in wound complications. We recently reported a novel family of biocompatible, biodegradable polymers, amino acid-based poly(ester amide)s (AA-PEA), which we have shown to significantly attenuate the foreign body inflammatory response in vitro. Two types of AA-PEA (Phe-PEA and Arg-Phe-PEA) were used to coat silk or plain-gut sutures, which were implanted in the gluteus muscle of C57BL/6 mice, while the uncoated control sutures were implanted in the contralateral side. After 3, 7, 14, and 28 days the mean area of inflammation surrounding the sutures was compared. Phe-PEA coating of silk sutures significantly decreased inflammation compared with noncoated controls (67.8 ± 17.4% after 3d [p = 0.0014], 51.6 ± 7.2% after 7d [p < 0.001], and 37.3 ± 8.3% after 28d [p = 0.0001]) when assessed via analysis of photomicrographs using digital image software. Phe-PEA coated plain-gut sutures were similarly assessed and demonstrated a significant decrease in the mean area of inflammation across all time points (54.1 ± 8.3% after 3 d, 41.4 ± 3.9% after 7 d, 71.5 ± 8.1% after 14 d, 78.4 ± 8.5%, and after 28 d [all p < 0.0001]). Arg-Phe-PEA coated silk demonstrated significantly less inflammation compared to noncoated controls (61.3 ± 9.4% after 3 d, 44.7 ± 4.7% after 7 d, 19.6 ± 8%, and 38.3 ± 6.8% after 28 d [all p < 0.0001]), as did coated plain-gut (37.4 ± 8.3% after 3 d [p = 0.0004], 55.0 ± 7.8% after 7 d [p < 0.0001], 46.0 ± 4.6% after 14 d [p < 0.0001], and 59.0 ± 7.9% after 28 d [p < 0.0001]). Both Phe-PEA and Arg-Phe-PEA coatings significantly decrease the inflammatory response to sutures in vivo for up to 28 days.

Perioperative Antibiotics in the Setting of Oropharyngeal Reconstruction: Less Is More.

BackgroundRecipient-site infection after oropharyngeal reconstruction is a potentially disastrous complication. Although studies suggest that perioperative antibiotics reduces infection rates in these patients from 87% to 20%, there is no consensus regarding what constitutes the most appropriate antibiotic regimen and duration of treatment. MethodsA retrospective review of perioperative antibiotic administration was performed of all patients who underwent local, pedicled, or free flap oropharyngeal reconstruction after oncologic resection by a single surgeon at a single institution between 2007 and 2013 to assess for recipient-site complications. ResultsNinety-seven patients underwent 100 reconstructions (61 free flap reconstructions, 39 pedicled/local flap reconstructions) and all received a combination of intravenous (IV) antibiotic agents designed to cover oral flora. There were 23 (23%) recipient-site complications, which included cellulitis (9%), mucocutaneous fistula (5%), abscess (5%), and wound dehiscence (4%). Duration of antibiotic prophylaxis, defined as less than 48 hours (short-course) or greater than 48 hours (long-course), was not a significant predictor of recipient-site complication. Significant risk factors for recipient-site complications were clindamycin prophylaxis (P < 0.008), increased duration of surgery (P < 0.047), and advanced age (P < 0.034). Recipient-site complication was found to be a significant predictor of both increased length of hospital stay (P < 0.001) and increased time to the resumption of enteral feeds (P < 0.035). ConclusionsThese data suggest that extended courses of perioperative antibiotics do not confer additional benefits in patients undergoing oropharyngeal reconstruction. We recommend a limited 48-hour course of prophylactic antibiotics with sufficient aerobic and anaerobic coverage to help minimize the incidence of antibiotic-related morbidities.

Vascular smooth muscle cell optimization of vasculogenesis within naturally derived, biodegradable, hybrid hydrogel scaffolds.

Background: As vascularization represents the rate-limiting step in permanent incorporation of hydrogel-based tissue-regeneration templates, the authors sought to identify the material chemistry that would optimize endothelial cell adhesion and invasion into custom hydrogel constructs. The authors further investigated induction of endothelial tubule formation by growth factor supplementation and paracrine stimulation. Methods: Hydrogel scaffolds consisting of combinations of alginate, collagen type I, and chitosan were seeded with human umbilical vein endothelial cells and maintained under standard conditions for 14 days. Cell density and invasion were then evaluated. Tubule formation was evaluated following basic fibroblast growth factor addition or co-culture with human aortic smooth muscle cells. Results: Human umbilical vein endothelial cells demonstrated greatest cell-surface density and invasion volumes with alginate and collagen (10:1 weight/weight) scaffolds (p < 0.05). Supplementation with basic fibroblast growth factor increased surface density but neither invasion nor tubule formation. A significant increase in tubule content/organization was observed with increasing human aortic smooth muscle cell–to–human umbilical vein endothelial cell ratio co-culture. Conclusions: Alginate and collagen 10:1 scaffolds allow for maximal cellularization compared with other combinations studied. Growth factor supplementation did not affect human umbilical vein endothelial cell invasion or morphology. Paracrine signaling by means of co-culture with human umbilical vein endothelial cells stimulated endothelial tubule formation and vascular protonetwork organization. These findings serve to guide future endeavors toward fabrication of prevascularized tissue constructs.

Management of Stenosing Flexor Tenosynovitis: Maximizing Nonoperative Success without Increasing Morbidity.

Background: Traditional nonoperative management of stenosing tenosynovitis is limited to one corticosteroid injection, followed by surgery in the case of failure. Recently, nonoperative strategies have been extended to include two or three injections despite the absence of large prospective studies supporting this practice. Methods: A prospective study was performed of all patients presenting with stenosing tenosynovitis to a single surgeon (R.S.R.) over a 22-year period. Patients with potentially confounding comorbidities were excluded. All digits received one to three injections of triamcinolone acetonide plus local anesthetic into the tendon sheath. Data were analyzed by digit. Results: Five hundred seventy-one digits (401 patients) were included. Digits that were symptomatic for 3 months or less were more likely to resolve after one injection than those that were symptomatic for more than 3 months (OR, 2.6; 95 percent CI, 1.67 to 4.0; p < 0.01). For the digits that failed to resolve after the first injection, those that were symptomatic for 5 months or less before one injection were more likely to respond to a second injection than those that were symptomatic for more than 5 months (OR, 9.4; 95 percent CI, 3.0 to 29.7; p < 0.01). Eight digits received three injections, after which six (75 percent) achieved remission. There were no instances of tendon/pulley rupture, infection, or soft-tissue atrophy. Conclusions: Stenosing tenosynovitis is more likely to respond to nonoperative therapy when treated before 3 months. It is safe and effective to administer more than one corticosteroid injection, as second and third doses increase the overall remission rate without increasing morbidity. CLINICAL QUESTION/LEVEL OF EVIDENCE: Therapeutic, IV.