Analysis of Acellular Dermal Matrix Integration and Revascularization following Tissue Expander Breast Reconstruction in a Clinically Relevant Large-Animal Model:

Vascularization of Human Acellular Dermal Matrices: A Comparative Study in a Nonhuman Primate Model

Four human acellular dermal matrices (hADMs) were characterized in a nonhuman primate abdominal wall repair model by evaluating host immune response, vascularization, and incorporation into host tissues. AlloDerm™ (electron beam-sterilized hADM [e-hADM]), AlloMax™ (gamma beam-sterilized hADM, freeze-dried [g-hADM-FD]), DermaMatrix™ (hADM, freeze-dried [hADM-FD]), and FlexHD™ (ethanol-treated hADM [EtOH-hADM]) were each implanted in an abdominal wall-bridging defect in nonhuman primates (n = 3 animals/time point, n = 36 animals). Immunohistochemical and histological assessments were conducted on biopsies from each hADM at 1-, 3-, and 6-months postimplantation to assess vascularization (hematoxylin and eosin [H&E], CD31, alpha smooth muscle actin [αSMA], collagen IV), inflammatory/immune response (H&E, CD3, CD20, CD68), and collagen turnover (H&E, matrix metalloproteinase-9 [MMP-9]). MMP-9 immunolabeling was similar among different hADMs at 1 month; however, hADM-FD and EtOH-hADM showed higher total mean MMP-9-immunopositive areas at approximately 16% compared with <1% for e-hADM and g-hADM at 6 months postimplantation. Cells that stained positively for CD68, CD3, and CD20 were generally higher for hADM-FD and EtOH-hADM compared with other hADMs. The mean CD31-immunopositive area, CD31 vessel density, CD31 vessel diameter, and collagen IV-immunopositive area increased over time. Among all the hADM types, e-hADM had the highest mean (±standard deviation [SD]) CD31-immunopositive area at 1.54% ± 1.01%, vessel density at 7.86 × 10-5 ± 3.96 × 10-5 vessels/µm2, and collagen IV-immunopositive area at 2.55% ± 0.73% 1-month postimplantation. The pattern of αSMA immunolabeling varied among the hADMs. Histology showed that overall inflammation was mild at 1 month. Overall fibroblast repopulation and collagen remodeling increased over time from 1 to 6 months postimplantation. Fibroblast infiltration was minimal to mild at 1 month, with e-hADM showing the highest mean (±SD) score at 2.00 ± 0.00 compared with other hADMs. Only hADM-FD was not completely replaced by neotissue formation at 6 months postimplantation. All hADMs promoted vascularization, cell infiltration, and incorporation into host tissue, which were associated with acute inflammation and immune responses, within a 6-month period. A trend toward relatively enhanced early vascularization in e-hADM compared with other hADMs was observed. Immunogenic responses among the hADMs in the present study showed a slight distinction toward more quiescent terminally sterilized hADMs (e-hADM, g-hADM-FD) versus aseptically processed hADMs (EtOH-hADM, hADM-FD).

Prepectoral Direct-to-Implant versus Staged Tissue Expander Breast Reconstruction: A Comparison of Complications

BACKGROUND

Direct-to-implant (DTI) reconstruction has multiple advantages over a staged tissue expander (TE) approach. However, its use may be limited by concerns of increased complications. This study is the largest series to date comparing postoperative outcomes for DTI versus TE reconstruction in the prepectoral plane.

METHODS

The authors retrospectively reviewed 348 patients who underwent 536 total immediate, prepectoral implant-based breast reconstructions between January of 2018 and December of 2021. The authors compared the presence of risk factors and the rate of six separate complications between patients who underwent DTI versus TE reconstruction up to 1 year after surgery.

RESULTS

Of 348 patients, 147 (42%) and 201 (58%) underwent TE and DTI reconstruction ( P = 0.1813), respectively. The overall infection rate was 16.4% ( n = 57). DTI patients had a significantly greater incidence of wounds ( P < 0.0001), including minor ( P < 0.0011) and major wounds ( P < 0.0053). Significantly greater mastectomy resection weights were found for DTI patients who experienced any complication ( P < 0.0076), postoperative wounds ( P < 0.0001), and major wounds specifically ( P < 0.0035). Compared with medium-thickness acellular dermal matrix (ADM), extra thick ADM was associated with significantly increased rates of infection ( P < 0.0408) and wounds ( P < 0.0001).

CONCLUSIONS

Prepectoral DTI reconstruction in patients with adequate flap perfusion may have complication rates comparable to staged TE reconstruction, apart from a higher incidence of postoperative wounds. Greater mastectomy resection weights and thickness of ADM may specifically contribute to infection and wound-healing complications. Prepectoral DTI reconstruction is encouraged in the patients with adequate flap perfusion and moderate to low mastectomy resection weights who desire comparable or smaller implant volumes.

CLINICAL QUESTION/LEVEL OF EVIDENCE

Therapeutic, III.

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.

Difference in the outcomes of anterior tenting and wrapping techniques for acellular dermal matrix coverage in prepectoral breast reconstruction

BACKGROUND

Acellular dermal matrices (ADMs) play an essential role in prepectoral implant-based breast reconstructions; however, the most appropriate method for ADMs is unknown.

METHODS

We conducted a retrospective analysis of our institutional database. Patients who underwent mastectomy and prepectoral breast reconstruction using tissue expanders or breast implants covered with ADMs between March 2018 and June 2021 were included. Patient characteristics, postoperative complications, and long-term outcomes were investigated.

RESULTS

In total, 112 patients (126 breasts) were included. The anterior tenting and wrapping techniques were used in the reconstruction of 32 (25.3%) and 94 (74.7%) breasts, respectively. Using propensity score matching, nine breasts were selected for each technique within the direct-to-implant reconstruction group, while 16 breasts were selected for each technique within the 2-stage reconstruction group. The choice of technique (anterior vs. wrapping) in implementing ADM did not generate any significant differences in postoperative complications, including seroma formation and capsular contracture, for the direct-to-implant and 2-stage reconstruction groups. Regarding the direct-to-implant reconstruction group, the average postoperative drain volume was less in the anterior tenting group than that in the wrapping group (anterior tenting vs. wrapping; 495.09 ± 156.118 mL vs. 673.43 ± 307.954 mL, p = 0.006), but the difference was insignificant after propensity score matching.

CONCLUSION

We report our experience with covering prosthetic devices with ADMs during postmastectomy breast reconstruction. No differences in the postoperative drain volume or postoperative outcomes were found between the study groups. Future studies are needed to determine the method that provides the most satisfactory results.

In vitro and in vivo evaluation of a modified porcine acellular dermal matrix for soft tissue augmentation

OBJECTIVES

To evaluate the effects of a modified porcine acellular dermal matrix (P-ADM), subepithelial connective tissue graft (SCTG) and other commercial bovine acellular dermal matrix membrane materials (B-ADM) on gingival soft tissue augmentation in the oral esthetic zone.

MATERIAL AND METHODS

The characteristics of P-ADM were observed by scanning electron microscope (SEM), Hematoxylin and eosin (H&E) and Masson's trichrome staining (Masson staining). The biocompatibility of P-ADM was verified by CCK8, phalloidin and living/dead cell staining. Beagle dog models were constructed and the thickness of gingiva was analyzed by the intraoral scanner. The morphology was observed by H&E and Masson staining.

RESULTS

Scanning electron microscopy, H&E and Masson staining showed that the P-ADM was mainly composed of collagen fibers, with no component of nuclear. The results of CCK8, phalloidin and living/dead cell staining indicated that the P-ADM had good cytocompatibility and no cytotoxicity. Human gingival fibroblasts were able to adhere and stretch on the surface of the material with pseudopodia. The SCTG group outperformed the B-ADM and P-ADM groups in terms of effectiveness, according to the analysis of digital oral scanning data at various time points following incremental soft tissue surgery. Compared with the B-ADM group, the effect of soft tissue increment was better in the P-ADM group.

CONCLUSIONS

P-ADM, as a biocompatible biomaterial, can be used as an alternative biomaterial for oral soft tissue thickening. However, the results of this study need to be verified by more clinical trials.

Co-Graft of Acellular Dermal Matrix and Split Thickness Skin Graft-A New Reconstructive Surgical Method in the Treatment of Hidradenitis Suppurativa

Hidradenitis suppurativa is a chronic disease that significantly reduces patients' quality of life. Patients are chronically treated with systemic therapies, which are often ineffective. Surgical treatment for severe cases of hidradenitis suppurativa is one option for affected patients. Surgical treatment has its limitations, and wound closure may be particularly problematic. This requires the use of reconstructive techniques. The methods of choice for wound closure are split-thickness skin grafts or local flaps reconstructions. However, each method has its limitations. This is a presentation of a new reconstructive surgical method in hidradenitis suppurativa surgery: the use of a co-graft of Acellular dermal matrix and split thickness skin graft as a novel method in wound closure after wide excisions, based on two cases. The results of this method are very promising: we achieved very fast wound closure with good aesthetic results regarding scar formation. In this paper, we used several examinations: laser speckle analysis, cutometer tests, and health-related quality of life (QoL) questionnaire to check the clinical impact of this method. Our initial results are very encouraging. ADM with STSG as a co-graft could be widely used in reconstructive surgery. This is a preliminary study, which should be continued in further, extended research.

[The Value of Synthetic and Biologic Meshes in Implant-Based Breast Reconstruction]

Implant based breast reconstruction (IBBR) keeps evolving and has been influenced heavily by the use of synthetic and biologic meshes in the last years. In both, subpectoral as well as prepectoral approaches the use of synthetic and biologic meshes has made it possible to place implants precisely according to the breast's footprint and strengthen soft-tissue coverage, particularly in the lower pole of the breast with lower complication rates and better cosmesis. Various mesh options that differ in material, processing, size and cost are currently in clinical use. This review aims to define the role of biologic and synthetic meshes in IBBR regarding the advantages and disadvantages of their use.

Implant-Based Breast Reconstruction after Mastectomy, from the Subpectoral to the Prepectoral Approach: An Evidence-Based Change of Mind?

Over the last years, prepectoral implant-based breast reconstruction has undergone a renaissance due to several technical advancements regarding mastectomy techniques and surgical approaches for the placement and soft tissue coverage of silicone implants. Initially abandoned due to the high incidence of complications, such as capsular contraction, implant extrusion, and poor aesthetic outcome, the effective prevention of these types of complications led to the prepectoral technique coming back in style for the ease of implant placement and the conservation of the pectoralis muscle function. Additional advantages such as a decrease of postoperative pain, animation deformity, and operative time contribute to the steady gain in popularity. This review aims to summarize the factors influencing the trend towards prepectoral implant-based breast reconstruction and to discuss the challenges and prospects related to this operative approach.

A Comparative Study of Breast Sensibility and Patient Satisfaction After Breast Reconstruction: Autologous, 2-Stage Implant-Based, and Prepectoral Direct-to-Implant Reconstruction

BACKGROUND

Currently, a variety of treatment modalities are implemented for breast reconstruction. However, clinical prognosis regarding sensory regeneration of the breast and patient-reported satisfaction remains underexamined. In this study, we aimed to compare breast sensibility after various reconstruction.

METHODS

We conducted a retrospective comparative study of all patients who underwent breast reconstruction between August 2016 and October 2019 at our institution. Acellular dermal matrixes were used to cover the implant inferolaterally in a dual-plane subpectoral approach and to wrap the implant in prepectoral direct to implant (DTI). The cutaneous tactile pressure threshold and patient satisfaction outcome were tested.

RESULTS

A total of 105 breasts were assessed, 30 breasts reconstructed with deep inferior epigastric perforator (DIEP) flap, 40 breasts reconstructed with 2-stage subpectoral implant, and 35 breasts reconstructed with prepectoral DTI. In the specific group-to-group analysis, DIEP and implant groups showed significant differences in sensory recovery, mainly in lateral areas of the reconstructed breast. In 2-stage reconstruction and DTI groups, there were no statistically significant differences. When comparing patient groups using only patients with follow-up lengths of more than 12 months, the difference was more clearly indicated (P = 0.049). Better sensory recovery predicted high satisfaction scores in patient-reported outcomes (P = 0.007).

CONCLUSIONS

We found that subpectoral implant reconstruction and DTI show no statistically significant differences in sensory recovery, and autologous DIEP flap reconstruction results in a better prognosis than prosthesis implant reconstruction. Furthermore, the clarity of the differences increased when the follow-up length was longer than 12 months. Better patient-reported satisfaction was associated with good breast sensibility.

Tissue Engineering in Skin Substitute

Thermal injuries may cause significant damage to large areas of the skin. Extensive and deep burn wounds require specialized therapy. The optimal method in the strategy of treating extensive, full thickness burns (III°) is the use of autologous split thickness skin grafts STSG (Busuioc et al. Rom J Morphol Embryol 4:1061-1067, 2012; Kitala D, Kawecki M, Klama-Baryła A, Łabuś W, Kraut M, Glik J, Ryszkiel I, Kawecki MP, Nowak M. Allogeneic vs. Autologous Skin Grafts in the Therapy of Patients with Burn Injuries: A Restrospective, Open-label Clinical Study with Pair Matching. Adv Clin Exp Med. 2016 Sep-Oct;25(5):923-929.; Glik J, Kawecki M, Kitala D, Klama-Baryła A, Łabuś W, Grabowski M, Durdzińska A, Nowak M, Misiuga M, Kasperczyk A. A new option for definitive burn wound closure - pair matching type of retrospective case-control study of hand burns in the hospitalized patients group in the Dr Stanislaw Sakiel Center for Burn Treatment between 2009 and 2015. Int Wound J. 2017 Feb 21. https://doi.org/10.1111/iwj.12720 . [Epub ahead of print]; Prim et al. May 24Wound Repair Regen., 2017; Grossova et al. Mar 31Ann Burns Fire Disasters 30:5-8, 2017). The main limitation of that method is the inadequate amount of healthy, undamaged skin (donor sites), which could be harvested and used as a graft. Moreover, donor sites are an additional wounds that require analgesic therapy, leave scars during the healing process and they are highly susceptible to infection (1-6). It must be emphasized that in terms of the treatment of severe, deep and extensive burns, and there should be no doubt that the search for a biocompatible skin substitute that would be able to replace autologous STSG is an absolute priority. The above-mentioned necessitates the search for new treatment methods of severe burn wounds. Such methods could consider the preparation and application of bioengineered, natural skin substitutes. At present, as the clinical standard considered by the physicians may be use of available biological skin substitutes, e.g., human allogeneic skin, in vitro cultured skin cells, acellular dermal matrix ADM and revitalized ADMs, etc. (Busuioc et al. Rom J Morphol Embryol 4:1061-1067, 2012; Kitala D, Kawecki M, Klama-Baryła A, Łabuś W, Kraut M, Glik J, Ryszkiel I, Kawecki MP, Nowak M. Allogeneic vs. Autologous Skin Grafts in the Therapy of Patients with Burn Injuries: A Restrospective, Open-label Clinical Study with Pair Matching. Adv Clin Exp Med. 2016 Sep-Oct;25(5):923-929.; Glik J, Kawecki M, Kitala D, Klama-Baryła A, Łabuś W, Grabowski M, Durdzińska A, Nowak M, Misiuga M, Kasperczyk A. A new option for definitive burn wound closure - pair matching type of retrospective case-control study of hand burns in the hospitalised patients group in the Dr Stanislaw Sakiel Center for Burn Treatment between 2009 and 2015. Int Wound J. 2017 Feb 21. https://doi.org/10.1111/iwj.12720 . [Epub ahead of print]; Prim et al. May 24Wound Repair Regen., 2017; Grossova et al. Mar 31Ann Burns Fire Disasters 30:5-8, 2017; Łabuś et al. FebJ Biomed Mater Res B Appl Biomater 106:726-733, 2018).

In Vivo Comparison of Three Human Acellular Dermal Matrices for Breast Reconstruction

BACKGROUND/AIM

Acellular dermal matrices (ADMs) have become popular in implant-based breast reconstruction. The aim of this study was to compare three commonly used ADM products in vivo in an animal model.

MATERIALS AND METHODS

The nucleic acid content (residual double-stranded DNA) and the levels of the remaining growth factors after decellularization were measured for each ADM. Cytocompatibility with ADMs was documented using NIH 3T3 mouse fibroblast cells. In vivo, the implanted ADMs were histologically evaluated at 1, 2, 3, and 6 months (n=5) using male 8-week-old Sprague-Dawley rats.

RESULTS

Fibroblasts grew in the SureDerm HD and DermACELL with no cytotoxicity. In a rat model, SureDerm HD and DermACELL incorporated more readily into the surrounding host tissue, as measured by rapid cell influx and collagen deposition, and showed more delayed tissue remodeling with decreased matrix metalloproteinases levels compared to AlloDerm.

CONCLUSION

SureDerm HD and DermACELL can be used as biological materials for breast reconstruction.

The Biomechanical Properties of Meshed versus Perforated Acellular Dermal Matrices (ADMs)

Background:

Acellular dermal matrices (ADMs) are used for soft tissue augmentation across surgical specialties. Since allograft incorporation depends on direct opposition between the ADM and a vascular bed, seroma formation can be detrimental to incorporation. Since most ADM products are available in many meshed and perforated forms, there is a lack of consistency between manufacture designs. We set out to determine the fluid egress properties and increase in surface area resulting from common cut patterns.

Methods:

Three ADM cut patterns were studied: 1 meshed and 2 perforated. We calculated the surface area of these modified ADM samples. Fluid was passed through each ADM, and time required for fluid passage was recorded. An ANOVA (P < 0.05) was used to determine if there was a significant difference in egress properties across the 3 patterns.

Results:

Meshing in a 1:1 pattern resulted in a 97.50% increase in surface area compared with the uncut product. In comparison, only a 0.30% increase resulted from Perforation Pattern #1 and a 0.59% increase resulted from Perforation Pattern #2. There was a significant difference in egress properties across the three cut patterns (P = 0.000). The average egress time of Mesh Pattern #1 was 1.974 seconds. The average egress time of Perforation Pattern #2 was 6.504 seconds, and of Perforation Pattern #1 was 10.369 seconds.

Conclusions:

Quantitative comparison revealed that meshing ADM significantly improves fluid egress and increases the surface area. Therefore, the use of meshed ADM tissue could improve the incorporation of ADM with the recipient, with improved patient outcomes.

In Vitro Analysis of Histology, Mechanics, and Safety of Radiation-free Pre-hydrated Human Acellular Dermal Matrix

Purpose

Acellular dermal matrix (ADM) supports tissue expanders or implants in implant-based breast reconstruction. The characteristics of ADM tissue are defined by the manufacturing procedure, such as decellularization, preservation, and sterilization, and are directly related to clinical outcomes. This study aimed to compare the properties of a new pre-hydrated-ADM (H-ADM-low) obtained using a decellularization reagent reduction process with a low concentration of detergent with those of radiation-sterilized H-ADM and freeze-dried ADM (FD-ADM).

Methods

ADMs were evaluated in terms of structure, mechanical quality, and cytotoxicity using histochemical staining, tensile strength testing, and in vitro cell viability analysis.

Results

The tissue structure of H-ADM-low (CGDERM ONE-STEP) was similar to that of native skin despite complete decellularization. By contrast, in FD-ADM, the tissue structure was damaged by the freeze-drying process, and radiation-sterilized H-ADM showed a compact fibrillar arrangement. Furthermore, matrix components such as collagen and elastin were preserved in H-ADM-low, whereas a loss of elastin fibers with fragmented distribution was observed in radiation-sterilized H-ADMs. H-ADM-low's tensile strength (58.84 MPa) was significantly greater than that of FD-ADM (38.60 MPa) and comparable with that of radiation-sterilized H-ADMs. The residual detergent content in H-ADM-low (47.45 mg/L) was 2.67-fold lower than that of H-ADM decellularized with a conventional detergent concentration (126.99 mg/mL), and this finding was consistent with the cell viability results (90.7% and 70.7%, respectively), indicating that H-ADM-low has very low cytotoxicity.

Conclusions

H-ADM-low produced through aseptic processes retains the original tissue structure, demonstrates excellent mechanical properties, and does not affect cell viability. Therefore, this newer H-ADM is suitable for use in implant-based breast reconstruction.

What happens to an acellular scar matrix after implantation in vivo? A histological and related molecular biology study

It has been established that scar acellular matrices (AMs), which allow cell proliferation, have similar characteristics. The aim of this study was to investigate the repair effect of scar AMs on animals, thus providing a reference for clinical application. Selected mature and immature scar AMs were implanted into animals, and then a negative control group was set for comparison. The effect of scar AMs on wound healing was observed through tissue staining, RT-qPCR, and immunohistochemistry. The materials showed milder inflammation and faster extracellular matrix (ECM) deposition than the negative control group. The ECM deposition and new vessels increased over time. However, the arrangement of ECM in mature scar AM was more regular than in immature scar AM and the negative control group, and more new vessels grew in the mature scar AM group than in the immature scar AM group and negative control group over the same period. The transforming growth factor-β level was elevated at one month, two months, and six months. COLA1 and vimentin levels all peaked at six months. Matrix metalloproteinase and TIMP1 were also elevated at different months. Collectively, scar AMs can effectively promote wound healing and vascularization. Mature scar AMs have a better regeneration effect.

Development of an evidence-based approach to the use of acellular dermal matrix in immediate expander-implant-based breast reconstruction

BACKGROUND

Although acellular dermal matrix (ADM) is widely used in expander-implant-based breast reconstructions, previous analyses have been unable to demonstrate improvements in patient-reported outcomes (PROs) with this approach over non-ADM procedures. This study aims to develop a more selective, evidence-based approach to the use of ADM in expander-implant-based breast reconstruction by identifying patient subgroups in which ADM improved clinical outcomes and PROs.

STUDY DESIGN

The Mastectomy Reconstruction Outcomes Consortium Study prospectively evaluated immediate expander-implant reconstructions at 11 centers from 2012 to 2015. Complications (any/overall and major), and PROs (satisfaction, physical, psychosocial, and sexual well-being) were assessed two years postoperatively using medical records and the BREAST-Q, respectively. Using mixed-models accounting for centers and with interaction terms, we analyzed for differential ADM effects across various clinical subgroups, including age, body mass index, radiation timing, and chemotherapy.

RESULTS

Expander-implant-based breast reconstruction was performed in 1451 patients, 738 with and 713 without ADM. Major complication risk was higher in ADM users vs. nonusers (22.9% vs. 16.4% and p = 0.04). Major complication risk with ADM increased with higher BMI (BMI=30, OR=1.70; BMI=35, OR=2.29, interaction p = 0.02). No significant ADM effects were observed for breast satisfaction, psychosocial, sexual, and physical well-being within any subgroups.

CONCLUSION

In immediate expander-implant-based breast reconstruction, ADM was associated with a greater risk of major complications, particularly in high-BMI patients. We were unable to identify patient subgroups where ADM was associated with significant improvements in PROs. Given these findings and the financial costs of ADM, a more critical approach to the use of ADM in expander-implant reconstruction may be warranted.

Persistent nipple discharge after nipple-sparing mastectomy secondary to unincorporated AlloDerm: a case report

Background

Rates of nipple-sparing mastectomies have increased over the past decade. In 2017, acellular dermal matrix was used in 56% of breast reconstructive procedures, with complication rates similar to operations without AlloDerm. Although persistent nipple discharge after nipple-sparing mastectomy is a rare event, it has been described in the literature. Other authors have described evaluation and treatment on a case-by-case basis. To the best of our knowledge, this is the first case report to describe a persistent unilateral discharge after multiple operative revisions and to provide an algorithmic approach to workup and treatment.

Case presentation

We present a case of a 29-year-old Hispanic woman with BRCA1 mutation who underwent a prophylactic bilateral nipple-sparing mastectomy with immediate reconstruction using AlloDerm. The year following her operation, the patient underwent two surgical revisions, one for implant rippling and one for asymmetry. Six months after her second revision, she presented to our hospital with a capsular contracture and unilateral clear nipple discharge. Her breast ultrasound showed dilated subareolar ducts and a suspicious mass. Magnetic resonance imaging identified a benign-appearing, rim-enhancing fluid collection. She underwent a third revision. One year later, she returned to our clinic with bloody nipple discharge, erythematous skin changes, and a palpable breast lump. Her surgical biopsy showed a fold in AlloDerm and chronic inflammatory changes. She continued experiencing discharge and opted for nipple excision. During the operation, a lacrimal probe demonstrated a direct connection between the discharging external duct and a seroma associated with an area of unincorporated AlloDerm. The section of unincorporated AlloDerm was excised, and no evidence of malignancy was identified. Ten months later, the patient remained symptom-free and had progressed to placement of final silicone implants.

Conclusions

To the best of our knowledge, this is the first case report to describe a nongravid patient with persistent unilateral sanguineous nipple discharge after multiple operative revisions. A visible communication between the draining duct and a seroma associated with unincorporated AlloDerm was ultimately identified. We present a clinical algorithm for patients with nipple discharge after nipple-sparing mastectomy.

Histopathological Study of Meshed Versus Solid Sheet Acellular Dermal Matrices in a Porcine Model

BACKGROUND

Acellular dermal matrices (ADMs) are commonly used to support implant-based breast reconstruction. However, there is little comparative data on the incorporation process of different ADMs, and the value of meshing or fenestration versus solid sheet has not been established, although early clinical data suggest seroma rates may be reduced. This was a preclinical assessment of the incorporation process at optimal conditions in a pig model.

METHODS

SurgiMend and AlloDerm matrices were implanted in subcutaneous pockets on the backs of 15-week-old female pigs. Half of the samples were meshed 1:2.5; the remainder was grafted as a fenestrated (SurgiMend) or solid sheet (AlloDerm). Tissues were harvested at 3 months. Histological slides were prepared for hematoxylin and eosin staining, and Masson trichrome and immunostaining with anticollagen type I fluorescein isothiocyanate stain. Histological parameters (inflammation, giant cell reaction, neovascularization, fibroplasias, and scar tissue formation) were graded blindly on a scale of 0 (no reaction) to 3 (severe reaction).

RESULTS

All explanted ADMs (SurgiMend, n = 23; AlloDerm, n = 20) were firmly incorporated within the host tissue. SurgiMend showed more fibroplasia (P = 0.029) compared with AlloDerm in meshed or solid sheet form. Meshed ADMs showed a trend toward increased inflammation (P = 0.074) and giant cell reaction (P = 0.053) compared with solid sheet/fenestrated ADM.

CONCLUSIONS

Meshing ADM may allow cells to populate matrices more rapidly, promoting integration compared with solid sheet ADMs. This study sets the histological basis for further clinical investigations, with the aim of demonstrating lower complication rates (and particularly reduced seroma formation) with meshed ADMs.

[Appllication of human acellular dermal matrix in surgical treatment of genitourinary disease]

Humanacellular dermal matrix (HADM) is widely used in the field of burn wound repair and tissue engineering plastic surgery. HADM is manufactored by physical and chemical decellular process to remove the antigenic components that might cause immune rejection in dermis.The extracellular matrix of three-dimensional cell scaffold structure with collagen fibers had been used for wound repair and tissue regeneration, while HADM characterized with low absorption rate after implantation and strong ability to induce angiogenesis in host tissue. Studies reported that after the HADM was implanted into the patient, the host cells, such as fibroblasts and myofibroblasts, as well as lymphocytes, macrophages, granulocytes and mast cells, rapidly infiltrated the graft. The connective tissue and neovascularization were then formed within the HADM three-dimensional cell scaffold, the lymphatic system also appears after vascular reconstruction. Traditional urethral reconstruction using autologous skin flaps has some defects, such as complexity of the technology, risk of necrosis of the skin flaps after transplantation, and failure to achieve functional repair of the urethral epithelium. It has been reported that using HADM to reconstruct the urethra in patients with urethral stricture, hypospadias and bladder-vaginal fistula, showed promising results. Others have reported the experience of using HADM to repair and reconstruct congenital classic bladder exstrophy. HADM has also been used for tissue repair in patients with penile skin defect caused by Fonier's gangrene and hidradenitis suppurativa, and implanted under Bucks' fascia to enlarge the penis. The report of HADM implantation for treating premature ejaculation also deserves attention. Researchers found that HADM implantation can form a tissue barrier between the skin and corpus cavernosum, which can effectively reduce penile sensitivity and treat premature ejaculation. The safety and effectiveness of HADM implantation in the treatment of premature ejaculation need to be further standardized by data from multi-center, large-sample clinical studies. In summary, HADM is the extracellular matrix and three-dimensional cell scaffold of human dermis. As a new type of tissue repair material, new blood vessels are formed actively after implantation, which shows good histocompatibility. HADM has shown increasingly broad application prospects in treatment of genitourinary diseases including penis, urethra and bladder diseases. HADM has also been used in the treatment of premature ejaculation in recent clinical studies, and its long-term safety and efficacy need to be further investigated.

Emerging progress on the mechanism and technology in wound repair

Normal wound repair is a dynamic and complex process involving multiple coordinated interactions between growth factors, cytokines, chemokines, and various cells. Any failure during the repair process may cause chronic wounds or scar formation, which increase the financial burden of patients due to repetitive treatments and considerable medical expenditures, and affect their quality of life. Nowadays, extensive efforts have been made to develop novel therapeutics for wound repair. Genetic engineering technology, tissue engineering technology, stem cell-based therapy, physical and biochemical technology, and vacuum-assisted closure technique have been proposed to be beneficial for wound repair, and shown considerable potential for improving the rate and quality of wound healing and skin regeneration. However, challenges remain as applying these techniques. As the development of cell biology and molecular biology, the understanding of the mechanism under wound repair has gradually deepened. As the growth of interdisciplinary research on physics, chemistry, biology, tissue engineering, and materials, the concept and technique relating wound repair for clinical application have rapidly developed. This article reviews the latest progress on the mechanism and technique in wound repair.

Prosthetic Breast Reconstruction and Red Breast Syndrome: Demystification and a Review of the Literature

Supplemental Digital Content is available in the text.

Red breast syndrome (RBS) represents an inflammatory condition that rarely occurs in the setting of acellular dermal matrix use after prosthetic reconstruction. It is characterized by erythema or rubor that occurs directly over the ADM, and its appearance resembles that of a cellulitis. There have been many explanations with regard to etiology, but none have addressed the physiologic alterations leading to the onset and resolution of RBS. RBS is postulated to be the result of lymphatic disruption and is self-limiting. Resolution is postulated to be the result of angiolymphatic regeneration and the re-establishment of lymphatic flow within the mastectomy skin flap and the ADM, resulting in the clearance of inflammatory mediators responsible for the localized erythema.

Porcine Acellular Peritoneal Matrix in Immediate Breast Reconstruction: A Multicenter, Prospective, Single-Arm Trial

BACKGROUND

Use of biological implants such as acellular dermal matrices in tissue expander breast reconstruction is a common adjunct to submuscular implant placement. There is a paucity of published prospective studies involving acellular matrices. The authors sought to evaluate a porcine-derived acellular peritoneal matrix product for immediate breast reconstruction.

METHODS

A prospective, single-arm trial was designed to analyze safety and outcomes of immediate tissue expander-based breast reconstruction with a novel porcine-derived acellular peritoneal matrix surgical mesh implant. Twenty-five patients were enrolled in this industry-sponsored trial. Patient demographics, surgical information, complications, histologic characteristics, and satisfaction (assessed by means of the BREAST-Q questionnaire) were evaluated.

RESULTS

Twenty-five patients (44 breasts) underwent mastectomy with immediate breast reconstruction using tissue expanders with acellular peritoneal matrix. Sixteen reconstructed breasts experienced at least one complication (36 percent). Seroma and hematoma occurred in one of 44 (2.3 percent) and two of 44 breasts (4.6 percent), respectively. Wound dehiscence occurred in four of 44 breasts (9.1 percent). Three subjects experienced reconstruction failure resulting in expander and/or acellular peritoneal matrix removal (6.8 percent); all failures were preceded by wound dehiscence. Histologic analysis showed cellular infiltration and product resorption. Results of the BREAST-Q demonstrated a level of postoperative patient satisfaction consistent with results in the available literature.

CONCLUSIONS

Prepared porcine-derived acellular peritoneal matrix is a safe adjunct in immediate two-stage tissue expander-based breast reconstruction. Further studies are required to determine efficacy compared to current commercially available acellular matrices.

CLINICAL QUESTION/LEVEL OF EVIDENCE

Therapeutic, IV.

Immediate Implant-Based Breast Reconstruction with Acellular Dermal Matrix: A Comparison of Sterile and Aseptic AlloDerm in 2039 Consecutive Cases

BACKGROUND

Sterile ready-to-use acellular dermal matrix, introduced as an alternative to aseptic freeze-dried acellular dermal matrix for implant-based breast reconstruction, has been investigated in a limited number of studies. This study compared outcomes in implant-based breast reconstruction with ready-to-use and freeze-dried acellular dermal matrix.

METHODS

The authors analyzed patients undergoing implant-based breast reconstruction with either freeze-dried or ready-to-use acellular dermal matrix, including demographics, clinical variables, and outcomes. An a priori power analysis was performed and logistic regression modeling was used to quantify the effect of acellular dermal matrix on outcomes while controlling for potential confounders.

RESULTS

A total of 1285 consecutive patients undergoing 2039 immediate prosthetic breast reconstructions constituted the population: 612 (n = 910 breasts) with freeze-dried matrix and 673 (n = 1129 breasts) with ready-to-use acellular dermal matrix. The freeze-dried matrix cohort had a significantly higher rate of explantation compared with the ready-to-use matrix cohort (18.0 percent versus 12.0 percent; p = 0.0036), but surgical-site infection, wound dehiscence, mastectomy flap necrosis, seroma, and hematoma did not differ significantly between groups. On multivariate regression, patients undergoing reconstruction with freeze-dried matrix, compared to ready-to-use matrix, did not have higher odds of experiencing surgical-site infections (OR, 1.064; p = 0.7455), but did have higher odds of explantation (OR, 1.570; p = 0.0161). Tobacco use (OR, 2.809; p = 0.0002) and body mass index (OR, 1.054; p < 0.0001) were also independent predictors of explantation.

CONCLUSION

Immediate implant-based breast reconstruction with sterile ready-to-use acellular dermal matrix has a comparable overall safety profile and a lower rate of prosthetic explantations compared with aseptic freeze-dried acellular dermal matrix.

CLINICAL QUESTION/LEVEL OF EVIDENCE

Therapeutic, III.

Pre-culture of adipose-derived stem cells and heterologous acellular dermal matrix: paracrine functions promote post-implantation neovascularization and attenuate inflammatory response

Heterologous acellular dermal matrix (ADM) has good biocompatibility and sufficient strength for clinical use for the repair of defects, tissue filling, and resurfacing of deep wounds. However, ADM tissue has such a compact structure that it can easily result in delayed vascularization after implantation. Moreover, in spite of the low immunogenicity of heterologous ADM, it can still cause varying degrees of inflammation in the host. These two drawbacks limit the efficacy and scope of clinical applications for heterologous ADM. Adipose-derived stem cells (ADSCs) have multiple effects on promoting vascularization and regulating immunological responses through paracrine signaling. Pre-culturing heterologous ADM with ADSCs may address these problems; however, it is unknown if ADSCs can exert their paracrine functions within a heterologous ADM microenvironment. This study examined the effect of porcine ADM (PADM) on the paracrine function of rat ADSCs (rADSCs) and showed that the expression of genes associated with inflammatory regulation, pro-angiogenesis factors, and stemness increased when rADSCs were seeded on PADM compared to rADSCs seeded on microplates. This indicates that PADM can provide a beneficial microenvironment for ADSCs to exert their paracrine function. After pre-culture, in vivo implanted rADSC-PADM exhibited improved vascularization and mitigated inflammatory response compared to untreated PADM. This study is the first to report that ADM can provide a suitable microenvironment for ADSCs and that pre-culturing improved the ADM implantation quality in vivo. These results suggest that it could be possible to apply heterologous ADM more effectively and broadly for repair and reconstruction treatments.

Advances in Regenerative Medicine and Tissue Engineering: Innovation and Transformation of Medicine

Humans and animals lose tissues and organs due to congenital defects, trauma, and diseases. The human body has a low regenerative potential as opposed to the urodele amphibians commonly referred to as salamanders. Globally, millions of people would benefit immensely if tissues and organs can be replaced on demand. Traditionally, transplantation of intact tissues and organs has been the bedrock to replace damaged and diseased parts of the body. The sole reliance on transplantation has created a waiting list of people requiring donated tissues and organs, and generally, supply cannot meet the demand. The total cost to society in terms of caring for patients with failing organs and debilitating diseases is enormous. Scientists and clinicians, motivated by the need to develop safe and reliable sources of tissues and organs, have been improving therapies and technologies that can regenerate tissues and in some cases create new tissues altogether. Tissue engineering and/or regenerative medicine are fields of life science employing both engineering and biological principles to create new tissues and organs and to promote the regeneration of damaged or diseased tissues and organs. Major advances and innovations are being made in the fields of tissue engineering and regenerative medicine and have a huge impact on three-dimensional bioprinting (3D bioprinting) of tissues and organs. 3D bioprinting holds great promise for artificial tissue and organ bioprinting, thereby revolutionizing the field of regenerative medicine. This review discusses how recent advances in the field of regenerative medicine and tissue engineering can improve 3D bioprinting and vice versa. Several challenges must be overcome in the application of 3D bioprinting before this disruptive technology is widely used to create organotypic constructs for regenerative medicine.

Revascularization of AlloDerm Used during Endoscopic Skull Base Surgery

Objectives  AlloDerm is an acellular dermal matrix often used for reconstruction throughout the body. AlloDerm has been shown to undergo revascularization when used to reconstruct soft tissue such as in abdominal wall reconstruction. In this study, the authors review the literature on revascularization of AlloDerm and demonstrate the histologic findings of AlloDerm after implantation during skull base reconstruction. Study Design  Literature review and case reports. Setting  Tertiary Care Institution Participants  Patients from a tertiary care institution Main Outcome Measures  Histologic slides are evaluated and compared with nonimplanted AlloDerm. Methods  The authors review a case of explanted AlloDerm that had been used for skull base reconstruction after endoscopic skull base surgery. Results  Upon reviewing the histologic slides of explanted AlloDerm to nonimplanted AlloDerm, we demonstrate revascularization of AlloDerm when used in skull base reconstruction. Representative slides will be included. Conclusions  AlloDerm undergoes revascularization when used for skull base reconstruction.

Non-integrated acellular dermal matrix in breast reconstruction: a case report

Acellular Dermal Matrices have become increasing popular in breast reconstruction especially in the last decade. There is a debate on whether Acellular Dermal Matrices increase the risk of complications or not. Common complications include infection, wound dehiscence, necrosis, seroma, haematoma, capsular contracture, extrusion, loss of implant and reconstruction failure. Non-integration is not listed as a typical complication to the use of Acellular Dermal Matrices. We report a case of a completely non-integrated Acellular Dermal Matrix following breast reconstruction in a patient without significant risk factors.

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.

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.

Impact of Acellular Dermal Matrix (ADM) Use Under Mastectomy Flap Necrosis on Perioperative Outcomes of Prosthetic Breast Reconstruction

BACKGROUND

There is conflicting data on the potential necrotic complications of acellular dermal matrix (ADM) use in breast reconstruction, and most studies focus on mastectomy flap necrosis as an outcome measure associated with ADM use. The aim of this study was to examine cases with necrotic complications with and without the use of ADM and to investigate whether ADM affected perioperative outcomes in cases with necrotic complications.

METHODS

Patients who experienced mastectomy flap necrosis following mastectomy with tissue expander placement between January 2009 and March 2015 were retrospectively reviewed. The primary outcome was explantation of the expander, and other associated outcomes such as seroma or infection were also recorded.

RESULTS

A total of 57 breasts with mastectomy flap necrosis were identified: 32 of which were in the non-ADM group and 25 in the ADM group. The rate of explantation was 28% (7/25) in the ADM group versus 6.3% (2/32) in the non-ADM group, which was significantly different (P = 0.034). The ADM group had a significantly higher rate of "major" infection requiring surgical debridement than the non-ADM group (P = 0.016). Multivariate analysis showed that the use of ADM was trending toward an increasing expander rate with borderline significance (P = 0.05).

CONCLUSION

This study demonstrated that ADM use under mastectomy flap necrosis was a potential risk for explantation of the expander and major infection. Surgeons should be cautious with the use of ADM with devascularized mastectomy skin flaps prone to necrosis.

LEVEL OF EVIDENCE III

This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266 .

Comparison of two cadaveric acellular dermal matrices for immediate breast reconstruction: A prospective randomized trial

AlloDerm RTU^® and AlloMaxTM are two acellular dermal matrices (ADMs) used in implant-based breast reconstruction. In this study, we examined whether different processing methods for the ADMs lead to a disparity in histologic, clinical, and financial outcomes after breast reconstruction. Thirty patients undergoing implant-based breast reconstruction were randomized into AlloMax or AlloDerm arms (n = 15, each). ADM was placed at the time of immediate reconstruction. Patients were evaluated for complications on postoperative days 7, 14, and 30. During implant exchange, ADM biopsies were taken and compared histologically for vascular and cellular infiltration. Patient satisfaction was evaluated using the BRECON-31 questionnaire 1 year after implant exchange. A cost analysis was performed comparing the two ADMs. Patient demographics and complication rates were similar between the two groups (p > 0.05). Histologically, vessel density and fibroblast/inflammatory cell infiltrate were greater on the dermal side than on the implant side (p < 0.01) in both ADMs, suggesting greater vascular and cellular in-growth from the dermal side. Vessel density in the middle portion of the Allomax biopsies was significantly higher than the same site in the Alloderm biopsies (p < 0.05). The extent of fibroblast/inflammatory cell infiltration was similar in both arms (p > 0.05). The BRECON-31 satisfaction questionnaire yielded similar responses across all metrics between the two study arms. The negotiated price was slightly different when comparing the two ADMs, with no significant difference in ADM reimbursement. In this study, AlloDerm RTU and AlloMax were successfully used for implant-based breast reconstruction with comparable outcomes.

A Review of the Use of Acellular Dermal Matrices in Postmastectomy Immediate Breast Reconstruction

Acellular dermal matrices (ADMs) are now commonly used in postmastectomy implant-based immediate breast reconstruction. In 2-stage reconstructions involving placement of a tissue expander followed by an implant, they can improve the aesthetic outcome and expedite the expansion process. The use of ADMs has also allowed for 1-stage immediate placement of an implant following mastectomy (direct-to-implant reconstruction). However, the use of ADMs is associated with an increased risk of certain types of complications. An understanding of the use of these materials is essential to the postoperative care of patients who undergo ADM-assisted breast reconstruction. In this article, the use of ADMs in postmastectomy immediate breast reconstruction is reviewed.

Does Acellular Dermal Matrix Thickness Affect Complication Rate in Tissue Expander Based Breast Reconstruction?

Background. While the benefits of using acellular dermal matrices (ADMs) in breast reconstruction are well described, their use has been associated with additional complications. The purpose of this study was to determine if ADM thickness affects complications in breast reconstruction. Methods. A retrospective chart review was performed including all tissue expander based breast reconstructions with AlloDerm (LifeCell, Branchburg, NJ) over 4 years. We evaluated preoperative characteristics and assessed postoperative complications including seroma, hematoma, infection, skin necrosis, and need for reintervention. We reviewed ADM thickness and time to Jackson-Pratt (JP) drain removal. Results. Fifty-five patients underwent 77 ADM-associated tissue expander based breast reconstructions, with average age of 48.1 years and average BMI of 25.9. Average ADM thickness was 1.21 mm. We found higher complication rates in the thick ADM group. Significant associations were found between smokers and skin necrosis (p < 0.0001) and seroma and prolonged JP drainage (p = 0.0004); radiated reconstructed breasts were more likely to suffer infections (p = 0.0085), and elevated BMI is a significant predictor for increased infection rate (p = 0.0037). Conclusion. We found a trend toward increased complication rates with thicker ADMs. In the future, larger prospective studies evaluating thickness may provide more information.

Acellular dermal matrices in breast reconstructions - a literature review

During the last two decades, acellular dermal matrices (ADM) have been more widely used in reconstructive procedures i.e. breast reconstructions. Several, both synthetic and biologic products derived from human, porcine and bovine tissue, have been introduced. Until this point postoperative complications for the acellular dermal matrices, as a group, have been the main focus. The purpose of this literature review is to summarize the current knowledge on the each biologic product used in breast reconstructions, including product specific complication frequencies. A systematic search of the literature was performed in the PubMed and EMBASE databases, identifying 55 relevant articles, mainly evidence level III. AlloDerm seems to be associated with severe complicating matters in the reconstructive process compared to other products. This could be due to the higher number of investigating studies relative to the others. The surgical area faces certain challenges comparing results, due to surgical variance, the data collection and follow-up. More well-defined guidelines and more high-evidence randomized studies could increase the overall level of evidence in this area.

A Meta-analysis of Postoperative Complications of Tissue Expander/Implant Breast Reconstruction Using Acellular Dermal Matrix

BACKGROUND

Acellular dermal matrix (ADM) is commonly used for tissue expander/implant breast (TE/I-based) reconstruction. But the relation between ADM and postoperative complications remains controversial. A few meta-analyses were conducted in 2011-2012 and the result revealed that ADM can increase the risk of complications. The purpose of our study is to offer updated evidence for ADM clinical application by analyzing the effect of ADM on complications of TE/I-based breast reconstruction.

METHODS

The literature published from January 2010 to February 2015 was searched in EMbase, Medline, Science Direct, the Cochrane Central Register of Controlled Trials (CENTRAL), CBMdisc, CNKI, VIP, and the references of those included studies were also searched by hand. According to inclusive criteria, 11 studies were selected and the values were extracted from the included literature. Complications with four different categories assigned for overall complications, infection, hematoma/seroma, and explantation were collected. RevMan 5.1 was used for meta-analysis. The evidence level was assessed by using the GRADE system.

RESULTS

Eleven published studies were included. The results showed that compared to the control group, the ADM group increased the rate of overall complications (OR = 1.33, 95% CI 1.03-1.70, p = 0.03), infection (OR = 1.47, 95% CI 1.04-2.06, p = 0.03), hematoma/seroma (OR = 1.66, 95% CI 1.13-2.44, p = 0.01), but there was no significant difference in explantation (OR = 1.37, 95% CI 0.89-2.11, p = 0.15). Based on the GRADE system, all the evidence was at level C and weak recommendation.

CONCLUSIONS

In TE/I-based breast reconstruction, ADM increased the incidence of overall complications, infection, and hematoma/seroma; the incidence of explantation remains unknown. For the poor quality of the original studies, a prudent choice is suggested; and more high-quality, large-sample studies are needed.

NO LEVEL ASSIGNED

This journal requires that authors assign a level of evidence to each submission to which Evidence-Based Medicine rankings are applicable. This excludes Review Articles, Book Reviews, and manuscripts that concern Basic Science, Animal Studies, Cadaver Studies, and Experimental Studies. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors http://www.springer.com/00266.

An in vivo analysis of Miromesh--a novel porcine liver prosthetic created by perfusion decellularization

BACKGROUND

Bioprosthetics derived from human or porcine dermis and intestinal submucosa have dense, homogenous, aporous collagen structures that potentially limit cellular penetration, undermining the theoretical benefit of a "natural" collagen scaffold. We hypothesized that Miromesh-a novel prosthetic derived from porcine liver by perfusion decellularization-provides a more optimal matrix for tissue ingrowth.

METHODS

Thirty rats underwent survival surgery that constituted the creation of a 4 × 1 cm abdominal defect and simultaneous bridged repair. Twenty rats were bridged with Miromesh, and 10 rats were bridged with non-cross-linked porcine dermis (Strattice). Ten Miromesh and all 10 Strattice were rinsed in vancomycin solution and inoculated with 10(4) colony-forming units of green fluorescent protein-labeled Staphylococcus aureus (GFP-SA) after implantation. Ten Miromesh controls were neither soaked nor inoculated. No animals received systemic antibiotics. All animals were euthanized at 90 d and underwent an examination of their gross appearance before being sectioned for quantitative bacterial culture and histologic grading. A pathologist scored specimens (0-4) for cellular infiltration, acute inflammation, chronic inflammation, granulation tissue, foreign body reaction, and fibrous capsule formation.

RESULTS

All but one rat repaired with Strattice survived until the 90-d euthanization. All quantitative bacterial cultures for inoculated specimens were negative for GFP-SA. Of nine Strattice explants, none received a cellular infiltration score >0, consistent with a poor tissue-mesh interface observed grossly. Of 10 Miromesh explants also inoculated with GFP-SA, seven of 10 demonstrated cellular infiltration with an average score of +2.7 ± 0.8, whereas sterile Miromesh implants received an average score of 0.8 ± 1.0. Two inoculated Miromesh implants demonstrated acute inflammation and infection on histology.

CONCLUSIONS

A prosthetic generated from porcine liver by perfusion decellularization provides a matrix for superior cellular infiltration compared with non-cross-linked porcine dermis.

The use of urinary bladder matrix in the treatment of trauma and combat casualty wound care

Treatment of combat injuries and resulting wounds can be difficult to treat due to compromised and evolving tissue necrosis, environmental contaminants, multidrug resistant microbacterial and/or fungal infections, coupled with microvascular damage and/or hypovascularized exposed vital structures. Our group has developed surgical care algorithms with identifiable salvage techniques to achieve stable, definitive wound coverage often with the aid of certain regenerative medicine biologic scaffold materials and advanced wound care to facilitate tissue coverage and healing. This case series reports on the role of urinary bladder matrix scaffolds in the wound care and reconstruction of traumatic and combat wounds. Urinary bladder matrix was found to facilitate definitive soft tissue reconstruction by establishing a neovascularized soft tissue base acceptable for second stage wound and skin coverage options within traumatic and combat-related wounds.

Histologic characterization of acellular dermal matrices in a porcine model of tissue expander breast reconstruction

BACKGROUND

Acellular dermal matrices (ADMs) have been commonly used in expander-based breast reconstruction to provide inferolateral prosthesis coverage. Although the clinical performance of these biologic scaffold materials varies depending on a number of factors, an in-depth systematic characterization of the host response is yet to be performed. The present study evaluates the biochemical composition and structure of two ADMs, AlloDerm(®) Regenerative Tissue Matrix and AlloMax™ Surgical Graft, and provides a comprehensive spatiotemporal characterization in a porcine model of tissue expander breast reconstruction.

METHODS

Each ADM was characterized with regard to thickness, permeability, donor nucleic acid content, (residual double-stranded DNA [dsDNA]), and growth factors (basic fibroblast growth factor [bFGF], vascular endothelial growth factor [VEGF], and transforming growth factor-beta 1 [TGF-β1]). Cytocompatibility was evaluated by in vitro cell culture on the ADMs. The host response was evaluated at 4 and 12 weeks at various locations within the ADMs using established metrics of the inflammatory and tissue remodeling response: cell infiltration, multinucleate giant cell formation, extent of ADM remodeling, and neovascularization.

RESULTS

AlloMax incorporated more readily with surrounding host tissue as measured by earlier and greater cell infiltration, fewer foreign body giant cells, and faster remodeling of ADM. These findings correlated with the in vitro composition and cytocompatibility analysis, which showed AlloMax to more readily support in vitro cell growth.

CONCLUSIONS

AlloMax and AlloDerm demonstrated distinct remodeling characteristics in a porcine model of tissue expander breast reconstruction.

Autologous Fat Transfer: The Progenitor Cell Response to Different Recipient Environments

BACKGROUND

Autologous fat transfer is a common procedure; however, results are variable and unpredictable.

OBJECTIVES

Stem cell responses to hypoxic environments need to be elucidated to determine which cell types contribute to graft survival.

METHODS

Acellular dermal matrix (ADM) envelopes were implanted in the subcutaneous tissues of 4 swine. In each swine, 2 envelopes were inserted as controls (ADM group), and 2 were placed and injected with 5 mL of autologous fat (ADM/fat group). Two additional envelopes were inserted and filled with 5 mL of fat and an omental pedicle (A/F/O group). Animals were sacrificed and the envelopes excised at 1, 2, 4, and 16 weeks. Specimens were analyzed histologically and/or with flow cytometry.

RESULTS

Fat was retained in ADM envelopes with and without a pedicle blood supply, although the percentage of volume retention was greater in the pedicled group. The peak number of mesenchymal progenitor cells within the ADM/fat group was significantly greater than the peak in the A/F/O group (P =.044), whereas endothelial progenitor cells in the ADM/fat group showed a prolonged increase through 4 weeks (P =.015 vs the A/F/O group at week 4). At 16 weeks, the interior surface of the matrix in the ADM/fat group had significantly more blood vessels than that of the ADM or A/F/O group (P = .0021 and .0036, respectively).

CONCLUSIONS

Injecting fat into hypoxic environments significantly increases the mesenchymal and endothelial progenitor cell responses and enhances the formation of blood vessels.