Vascular Pedicle and Microchannels: Simple Methods Toward Effective In Vivo Vascularization of 3D Scaffolds.

Poor vascularization remains a key limiting factor in translating advances in tissue engineering to clinical applications. Vascular pedicles (large arteries and veins) isolated in plastic chambers are known to sprout an extensive capillary network. This study examined the effect vascular pedicles and scaffold architecture have on vascularization and tissue integration of implanted silk scaffolds. Porous silk scaffolds with or without microchannels are manufactured to support implantation of a central vascular pedicle, without a chamber, implanted in the groin of Sprague Dawley rats, and assessed morphologically and morphometrically at 2 and 6 weeks. At both time points, blood vessels, connective tissue, and an inflammatory response infiltrate all scaffold pores externally, and centrally when a vascular pedicle is implanted. At week 2, vascular pedicles significantly increase the degree of scaffold tissue infiltration, and both the pedicle and the scaffold microchannels significantly increase vascular volume and vascular density. Interestingly, microchannels contribute to increased scaffold vascularity without affecting overall tissue infiltration, suggesting a direct effect of biomaterial architecture on vascularization. The inclusion of pedicles and microchannels are simple and effective proangiogenic techniques for engineering thick tissue constructs as both increase the speed of construct vascularization in the early weeks post in vivo implantation.

Fate of Free Fat Grafts with or without Adipogenic Adjuncts to Enhance Graft Outcomes.

BACKGROUND: Free fat grafting is popular, but it is still unclear how it works. Although focusing on graft survival seems an obvious direction for improving clinical results, the authors' research suggests that long-term volume retention is in part attributable to new fat regeneration. Measures to facilitate adipogenesis may therefore be equally important. METHODS: To investigate the relative roles of survival and regeneration of fat grafts, the authors measured the fate of human lipoaspirate implanted into the scalps of immunodeficient mice, with and without stromal vascular fraction and a porcine extracellular matrix (Adipogel). Specifically, the authors were interested in volume retention, and the composition of implanted or regenerated tissue at 6 and 12 weeks. RESULTS: Free fat grafts exhibited poor volume retention and survival. Almost all of the injected human adipocytes died, but new mouse fat formed peripheral to the encapsulated fat graft. Adipogel and stromal vascular fraction improved proliferation of murine fat and human vasculature. Human CD34 stromal cells were present but only in the periphery, and there was no evidence that these cells differentiated into adipocytes. CONCLUSIONS: In the authors' model, most of the implanted tissue died, but unresorbed dead fat accounted substantially for the long-term, reduced volume. A layer of host-derived, regenerated adipose tissue was present at the periphery. This regeneration may be driven by the presence of dying fat, and it was enhanced by addition of the authors' adipogenic adjuncts. Future research should perhaps focus not only on improving graft survival but also on enhancing the adipogenic environment conducive to fat regeneration.

Steroid therapy for problematic proliferating haemangioma.

AIM: To evaluate the effectiveness and the safety of systemic and intralesional steroid therapy for problematic proliferating haemangioma. METHOD: 233 patients with haemangioma were identified from our vascular anomalies database 1996-2007. 46 (36%) out of 129 patients with proliferating haemangioma required intervention. 24 of these patients received steroid therapy. Indications for steroid therapy, the response and side effects of treatment and the need for other treatment were recorded. Intralesional triamcinolone up to 4 mg/kg/injection was preferred for small, localised non-periorbital lesions in 5 patients and oral prednisolone 2.0-2.5 mg/kg/day was used for larger lesions, especially around the periorbital region in 19 patients. RESULTS: Accelerated regression of the haemangioma was observed in four of the five patients who received intralesional triamcinolone and there was no complication. Overall, the haemangioma in 17 (89%) of the 19 patients responded to high dose oral prednisolone with accelerated regression noted in 10 (53%) patients. Rebound growth was observed in 5 patients during dose tapering, requiring dose increment in three patients and debulking surgery in one patient. Three patients developed growth retardation during treatment but this normalised 3-10 months following cessation of steroid therapy. Other side effects included mild Cushingoid features (n=2), irritability (n=2), increased appetite (n=3). CONCLUSION: Intralesional and systemic steroid are relatively safe and effective in treating problematic proliferating haemangioma. Systemic steroid therapy is associated with few short-term side effects. A multidisciplinary management is essential. Propranolol is likely to replace steroid as the first-line treatment for problematic proliferating haemangioma.

Ivory osteoma of the craniofacial skeleton.

The authors describe the clinical presentation, investigation, and surgical management of two cases of benign ivory osteoma of the craniofacial skeleton. In the first case, a bony mass located over the frontal region had become a cosmetic burden to the patient, and she requested removal with minimal morbidity. Accordingly, an endoscopic procedure, with minimal access incisions located behind the hairline, was devised. In the second case, the patient, a Jehovah's Witness, presented with a long history of slowly enlarging bony masses over the maxilla and in the pterygopalatine space. She finally requested surgical intervention when the symptoms of pain related to fifth nerve compression at the foramen ovale became intolerable. Key aspects of the preoperative and perioperative management strategies used to avoid blood transfusion are detailed, as is the surgical approach, which included a bicoronal scalp flap with temporary removal of the zygomatic arch and the coronoid process. Finally, the etiology, histology, and natural history of ivory osteomas are discussed.