Evaluation of lymphangiogenesis in acellular dermal matrix

How Porcine Acellular Dermal Matrix Influences the Development of the Breast Capsule 1 Year after Implantation: A Histopathological Analysis

Background

In prepectoral breast reconstruction (PPBR) the acellular dermal matrix (ADM)'s integration capacity into the tissue is known. The aim of this study was to analyze the effect of the ADM on development and composition of the peri-implant breast capsule in a dynamic setting of breast tissue expansion during two-stage prepectoral breast reconstruction.

Methods

This is a prospective single-center study in which 50 patients who underwent mastectomy and breast reconstruction with prepectoral tissue expander and Braxon ADM (group A) and submuscular tissue expander (group B) were enrolled. One-year post implantation hematoxylin & eosin (H&E) staining and immunohistochemistry analyses were done on capsule tissue samples.

Results

The analysis conducted on H&E-stained samples showed a significant reduction of cellular density and a decrease of the cellular infiltration in capsules of ADM-covered expanders compared with naked expander capsules (P < 0.05). The immunohistochemical analyses showed that group A capsules presented significantly less M1 CD68+ macrophages (P < 0.05), lower alfa-SMA expression levels, and a lower number of myofibroblasts (P < 0.05) compared with group B capsules. Presence of lymphatic vessels was minimally detected in both groups.

Conclusions

The ADM presence around the prepectoral tissue expander influences the development of the peri-implant capsule, causing a significant reduction of the number of cells and inflammatory infiltrate, especially M1 macrophages and myofibroblasts. The ADM Braxon is therefore effective in creating a noninflamed capsule around the implant and in dynamic tissue conditions, and such an environment is maintained in time.

Long-Term Ultrasonographic and Histologic Changes in Acellular Dermal Matrix in Implant-Based Breast Reconstructions

BACKGROUND

Acellular dermal matrix (ADM) is composed of extracellular matrix (ECM) and is widely used in implant-based breast reconstructions. However, long-term changes in the ADM around implants have not been established. This study aimed to investigate long-term changes in the ADM covering breast implants using serial ultrasound and histologic evaluations.

METHODS

The authors evaluated the ultrasound results of 145 patients who underwent implant-based breast reconstructions with ADM coverings. The ultrasound results obtained within 18 months of surgery and those obtained 5 years postoperatively were analyzed to determine the change in ADM thickness. For histologic analysis, the ADM was harvested from 30 patients who underwent secondary breast surgery. Histologic features of the ECM and cellular components within the ADM were compared at specific intervals from ADM implantation and the second operation (early ADM group, <18 months; late ADM group, >5 years postoperatively).

RESULTS

The ADM thickness on ultrasound examination was significantly decreased in the late ADM group compared with that in the early ADM group ( P < 0.001). Histologic analyses revealed that the late ADM group had less thickness with lower ECM levels versus the early ADM group. Increased infiltration of host cells, such as vascular endothelial cells, myofibroblasts, and immune cells, occurred in the late ADM group.

CONCLUSIONS

Implanted ADMs underwent gradual thinning over time, in addition to ECM reduction and infiltration of host cells. These findings are useful in understanding the natural course of ADMs currently used in implant-based breast reconstructions.

CLINICAL QUESTION/LEVEL OF EVIDENCE

Therapeutic, V.

Acellular Dermal Matrix Favorably Modulates the Healing Response after Surgery

SUMMARY

When first described for breast reconstruction, the presence of acellular dermal matrices (ADM) was associated with increased seroma formation and infection. However, clinical safety data has gradually improved with surgeon experience to an acceptable outcomes profile of ADM-assisted reconstruction when compared to submuscular implant coverage. In fact, ADM use potentially decreases capsular contracture rates and facilitates expansion for staged pre-pectoral breast reconstruction. Due to new regulatory requirements, the collection of unbiased, well-powered pre-market approval data summarizing long-term clinical outcomes will be essential over the coming years to understand the clinical performance of ADM usage in breast reconstruction.Currently, we can highlight the physiologic benefits of ADM use in breast reconstruction by evaluating the components of surgical wound healing that are favorably augmented by the implanted collagen substrate. ADM takes advantage of the wound healing cascade to incorporate into the patient's tissues - a process that requires a coordinated inflammatory infiltrate and angiogenesis. The presence of ADM augments and modulates the wound healing process to its advantage by simultaneously increasing the invasion of appropriate cellular constituents to facilitate expeditious healing and accelerate angiogenesis. Herein, we summarize the wound healing literature to demonstrate the mechanisms ADM use to biointegrate and the literature in which cellular constituents and soluble growth factors are upregulated in the presence of ADM. Lastly, we use our experimental observations of ADM incorporation to corroborate the literature.

Biologics and acellular dermal matrices in head and neck reconstruction: A comprehensive review

Acellular dermal matrices (ADMs) have been studied extensively in the literature and have gained popularity for various reconstructive and aesthetic purposes. ADMs are composed of a basement membrane and acellular dermal layer of collagen and provide a platform for mucosal epithelization and neovascularization. Combining dermal collagen and essential growth factors allows ADMs to support adequate wound healing and bolster soft-tissue repairs. These dermal matrices can be derived from human cadaveric donor skin (allogenic) or mammalian donor sources (xenogeneic). These dermal substitutes provide the benefit of reducing or eliminating the need for autologous tissue grafts and subsequently minimize donor site morbidity. Many ADMs are currently available in the market, each with variations in processing, manufacturing, storage, preparation, and use. The literature validating ADMs in the head and neck for both cosmetic and reconstructive purposes is evolving rapidly. This review aims to provide an up-to-date and comprehensive overview of the principles of acellular dermal matrices (ADMs), the different types of ADMs, and evaluate common indications, techniques, and outcomes pertaining to select anatomic sites in the head and neck reconstruction.

What happens to an acellular dermal matrix after implantation in the human body? A histological and electron microscopic study

Acellular matrices are used for various purposes and they have been studied extensively for their potential roles in regenerating tissues or organs. The acellular matrix generates physiological cues that mimic the native tissue microenvironment. Acellular dermal matrix (ADM) is a soft connective tissue graft generated by a decellularization process that preserves the intact extracellular skin matrix. Upon implantation, this structure serves as a scaffold for donor-side cells to facilitate subsequent incorporation and revascularization. In breast reconstruction, ADM is used mainly for lower pole coverage and the shaping of a new breast. It helps control the positioning of the implant in the inframammary fold, and prevents the formation of contractile pseudocapsule around the breast implant. In this study, we provide a comprehensive histological description of ADM used for human breast reconstruction over the course of several months following implementation. Using immunohistochemical methods (a panel of 12 antibodies) coupled with optical and transmission electron microscopy, we confirmed that the original acellular dermal matrix became recolonized by fibroblasts and myofibroblasts, and also by various other free cells of the connective tissue (lymphocytes, macrophages and multinucleated giant cells, granulocytes, mast cells) after implantation into the patient’s body. Within the implanted ADM, there was a relatively rapid ingrowth of blood vessels. Lymphatic vessels were only detected in one case 9 months after the implantation of the ADM. These results suggest that lymphangiogenesis is a longer process than angiogenesis.

Delayed post mastectomy breast reconstructions with allogeneic acellular dermal matrix prepared by a new decellularizationmethod

Acellular dermal matrix (ADM) is a tissue graft of allogeneic origin from post-mortem tissue donors prepared by an innovative decellularization process. The newly developed non-toxic and low cost decellularization process of cadaver origin dermis included ADM in breast reconstruction procedures proved to help coverage of the lower-pole of breast expanders or implants. As the results have shown, it did help to eliminate autologous dermis donor site morbidity along with shortening the operation time by avoiding elevation of additional muscle or fascia during the operation. Main aims of this article include histology evaluation of allogeneic acellular dermal matrix prepared by a new decellularization method and presentation of clinical results of its use. A total of 22 patients underwent 26 ADM based breast reconstructions. The mean patient's follow up was 12.6 months. Average total size of ADM used for one breast was 273 cm². Post-operative complications occurred in 3 patients including one expander infection, one expander extrusion and one expander pocket disfiguration. Microscopic analysis of tissue samples has confirmed incorporation of the acellular dermal matrices into the surrounding connective tissue without any noticeable immune reaction. In a majority of the ADM samples we found pseudocapsullar formation on implant side of samples without acute or chronic inflammatory cells. The use of ADM prepared by new preparation method in expansive post mastectomy breast reconstruction was associated by a relatively low complication rate resulting in good outcomes.

Sandwich Fascial Anterolateral Thigh Flap in Head and Neck Reconstruction: Evolution or Revolution?

Supplemental Digital Content is available in the text.

Introduction:

The anterolateral thigh perforator flap (ALT) represents the workhorse for most reconstructive efforts in the head and neck regions. The main advantages of this flap are its versatility, the length of the pedicle, and the low morbidity of the donor site. The major drawback is the bulkiness of this flap with the frequent need for secondary revisions. To overcome this, we have developed a novel way to harvest and inset the ALT, called the sandwich fascial ALT flap (SALT).

Methods:

All patients undergoing head and neck reconstruction using the SALT flap from January 2013 to March 2016 were included in this retrospective analysis. The SALT flap was harvested as a composite flap including the superficial fascia, the subscarpal fat, and the deep fascia. At the recipient site, the flap was inset with the deep fascia facing out. A split thickness skin graft (± dermal substitute) was used to cover the deep fascia and the pedicle.

Results:

Eleven patients were included: 8 cases of orbital exenteration, 1 case of forehead reconstruction, and 2 cases of palatal reconstruction after radical maxillectomy. Flap survival was 100%. One patient required an early take back for venous thrombosis. The reconstruction was effective in all cases, allowing a prosthetic rehabilitation when required. Donor-site morbidity was minimal.

Conclusions:

The reconstruction of head and neck defects with a bulky fasciocutaneous ALT flap might not be the best option in every case. The SALT flap could represent a valid alternative for selected cases, with encouraging functional and cosmetic outcomes.