Prepectoral Immediate Direct-to-Implant Breast Reconstruction with Anterior AlloDerm Coverage.

BACKGROUND: Staged subpectoral expander-implant breast reconstruction is widely performed. Disruption of the pectoralis major origin and the frequent occurrence of animation deformity and functional discomfort associated with subpectoral reconstruction remain ongoing concerns. Prepectoral single-stage direct-to-implant reconstruction resolves many of these issues. In this study, the authors explored the rationale for prepectoral single-stage implant-based breast reconstruction with anterior AlloDerm coverage as an alternative to the staged approach. METHODS: Seventy-three breasts in 50 patients were reconstructed using a single-stage direct-to-implant prepectoral approach with total anterior AlloDerm coverage during a 24-month period. The decision to proceed with single-stage reconstruction was predicated upon the adequacy of mastectomy skin flap blood flow based on indocyanine green fluorescence perfusion assessment. The patients were followed up for a maximum of 32 months. RESULTS: Ninety-seven percent of patients achieved complete healing within 8 weeks. There were 2 implant losses (2.7%) due to infection. Major seroma rate requiring repeated aspiration and drain insertion was 1.2%. There were no full-thickness skin losses. Capsular contracture was 0% in nonradiated patients. There were no cases of animation deformity. The authors were unable to establish significant correlation between complications and any of the usually stated risk factors, such as smoking, obesity, and large mastectomy weights, presumably due to the rigorous application of intraoperative skin perfusion assessment. CONCLUSION: Single-stage direct-to-implant reconstruction using a prepectoral approach appears to be a safe and effective means of breast reconstruction in many patients, assuming adequate skin perfusion is present.

In vivo quantitative and qualitative assessment of foreign body giant cell formation on biomaterials in mice deficient in natural killer lymphocyte subsets, mast cells, or the interleukin-4 receptorα and in severe combined immunodeficient mice.

In previous studies that explored the influence of cytokines on foreign body giant cell (FBGC) formation, we focused on interleukin (IL)-4 and IL-13, each of which was discovered to induce macrophage fusion leading to FBGC formation in vitro. Two correlative in vivo studies also confirmed that IL-4 plays a role in FBGC formation on implanted biomaterials, but that T lymphocytes are not the source of IL-4 or other cytokines that support this process. The present study focused on identification of the cellular source of macrophage fusion-inducing cytokines, including natural killer (NK) or NKT lymphocytes and mast cells using mouse models genetically deficient in each of these cell types, as well as IL-4 receptor alpha(IL-4Rα)-deficient and severe combined immunodeficient (SCID) mice. Polyetherurethane (PEU) and polyethylene terephthalate (PET) polymers were subcutaneously implanted and retrieved after 14, 21, or 28 days. FBGC formation was evaluated using quantitative and qualitative data from retrieved polymer surfaces. Both types of data indicate that, compared to normal control mice, neither NK or NKT lymphocytes nor mast cells are required for FBGC formation. Furthermore, FBGC formation on biomaterials can proceed in IL-4Rα-deficient and in SCID mice. Similar conclusions were made regarding FBGC formation on both PEU and PET biomaterials. These data suggest that other sources of IL-4/IL-13 and/or additional macrophage fusion-inducing cytokines can mediate FBGC formation on implanted biomaterials, or that, in the absence of normal primary pathways, FBGC formation is nevertheless supported by redundant innate mechanisms.

Controlling fibrous capsule formation through long-term down-regulation of collagen type I (COL1A1) expression by nanofiber-mediated siRNA gene silencing.

The foreign body reaction often interferes with the long-term functionality and performance of implanted biomedical devices through fibrous capsule formation. While many implant modification techniques have been adopted in attempts to control fibrous encapsulation, the outcomes remained sub-optimal. Nanofiber scaffold-mediated RNA interference may serve as an alternative approach through the localized and sustained delivery of siRNA at implant sites. In this study, we investigated the efficacy of siRNA-poly(caprolactone-co-ethylethylene phosphate) nanofibers in controlling fibrous capsule formation through the down-regulation of collagen type I (COL1A1) in vitro and in vivo. By encapsulating complexes of COL1A1 siRNA with a transfection reagent (Transit TKO) or the cell penetrating peptides CADY or MPG within the nanofibers (550-650 nm in diameter), a sustained release of siRNA was obtained for at least 28 days (loading efficiency ~60-67%). Scaffold-mediated transfection significantly enhanced cellular uptake of oligonucleotides and prolonged in vitro gene silencing duration by at least 2-3 times as compared to conventional bolus delivery of siRNA (14 days vs. 5-7 days by bolus delivery). In vivo subcutaneous implantation of siRNA scaffolds revealed a significant decrease in fibrous capsule thickness at weeks 2 and 4 as compared to plain nanofibers (p<0.05). Taken together, the results demonstrated the efficacy of scaffold-mediated siRNA gene-silencing in providing effective long-term control of fibrous capsule formation.

The integration of disparity, shading and motion parallax cues for depth perception in humans and monkeys.

A visual stimulus display was created that enabled us to examine how effectively the three depth cues of disparity, motion parallax and shading can be integrated in humans and monkeys. The display was designed to allow us to present these three depth cues separately and in various combinations. Depth was processed most effectively and most rapidly when all three cues were presented together indicating that these separate cues are integrated at yet unknown sites in the brain. Testing in humans and monkeys yielded similar results suggesting that monkeys are a good animal model for the study of the underlying neural mechanisms of depth perception.