Evaluation of Sidestream Darkfield Microscopy for Real-Time Imaging Acellular Dermal Matrix Revascularization

A Histological Comparison of Two Human Acellular Dermal Matrix Products in Prosthetic-Based Breast Reconstruction

Background

Acellular dermal matrices (ADMs) are an integral component of breast reconstruction. The ideal matrix would be relatively immuno-inert, allow rapid vascularization, and be affordable. The purpose of this study was to histologically compare 2 commonly used ADM products.

Methods

This is a prospective histological study of 17 patients (20 breasts) following prosthetic-based breast reconstruction with ADM: Alloderm (LifeCell Corp, Branchburg, N.J.) or Cortiva (RTI Surgical, Alachua Fla.). Biopsies were taken from the dermal matrix and natural capsules surrounding the expander/implant during secondary surgery [Range, 72-694 days (mean, 217 days)]. Biopsy specimens were prepared via hematoxylin and eosin, Masson's trichrome, elastin, and transforming growth factor (TGF)-1 stains. Quantitative analysis of staining was performed with ImageJ software. The clinical outcome of each patient is analyzed in relation to capsule architecture and ADM performance.

Results

There were 7 breasts in the Alloderm group and 13 in the Cortiva group. Both groups had similar demographic, aesthetic results, and complication profiles. The TGF-1 staining demonstrated significantly lower levels in the Cortiva capsules (P = 0.0139). The percentage of elastin and collagen are similar in the Cortiva, Alloderm, and natural peri-implant capsules. The native capsules show a significantly greater number of blood vessels when compared with Cortiva and Alloderm (P = 0.0371 and P = 0.0347, respectively); however, there is no difference in vascular pattern between the 2 dermal matrices.

Discussion

Postoperatively, Cortiva demonstrates equal vascularity with less TGF-1 activation compared with Alloderm. The clinical success and complication profile were similar between the Alloderm and Cortiva patients.

Advanced Imaging Techniques for Investigation of Acellular Dermal Matrix Biointegration

BACKGROUND

Biointegration, a concept involving a dynamic interplay among three processes-inflammation, cellular infiltration, and angiogenesis-is key to understanding the interaction between acellular dermal matrices and the host. The current standard for evaluating acellular dermal matrix biointegration involves histologic analysis at fixed time points; however, the authors' approach uses advanced imaging techniques to serially assess biointegration in real time.

METHODS

The authors have adapted two advanced imaging techniques-two-photon microscopy and photoacoustic microscopy-to investigate biointegration in a murine deepithelialized dorsal skin-fold window chamber model, specifically engineered to recapitulate the host microenvironment of acellular dermal matrix-assisted breast reconstruction. Four mice per group were assessed. Two-photon imaging of dual-transgenic mice allows for detection of fluorescently labeled perivascular cells, and macrophage lineage cells. Photoacoustic microscopy noninvasively assesses oxygen and hemoglobin concentration in living tissues, generating high-resolution, three-dimensional mapping of the nascent acellular dermal matrix-associated microvasculature and metabolic consumption of oxygen. These outcomes were corroborated by confirmatory histologic analysis at the terminal time point.

RESULTS

The acellular dermal matrix/host interface is characterized by robust inflammation (0 to 3 days), increased oxygen consumption and neoangiogenesis in the matrix border zone (10 to 14 days), and vascular and inflammatory cell penetration into the center of the matrix (>21 days).

CONCLUSION

The data broaden the core knowledge of acellular dermal matrix biology, and serve as a potential template for elucidating the key differences among various commercially available and developmental products to guide the reconstructive surgeon to better select a reconstructive adjunct that meets their specific needs.