A New Human-Derived Acellular Dermal Matrix for Breast Reconstruction Available for the European Market: Preliminary Results

Decellularization and Their Significance for Tissue Regeneration in the Era of 3D Bioprinting

Three-dimensional bioprinting is an emerging technology that has high potential application in tissue engineering and regenerative medicine. Increasing advancement and improvement in the decellularization process have led to an increase in the demand for using a decellularized extracellular matrix (dECM) to fabricate tissue engineered products. Decellularization is the process of retaining the extracellular matrix (ECM) while the cellular components are completely removed to harvest the ECM for the regeneration of various tissues and across different sources. Post decellularization of tissues and organs, they act as natural biomaterials to provide the biochemical and structural support to establish cell communication. Selection of an effective method for decellularization is crucial, and various factors like tissue density, geometric organization, and ECM composition affect the regenerative potential which has an impact on the end product. The dECM is a versatile material which is added as an important ingredient to formulate the bioink component for constructing tissue and organs for various significant studies. Bioink consisting of dECM from various sources is used to generate tissue-specific bioink that is unique and to mimic different biometric microenvironments. At present, there are many different techniques applied for decellularization, and the process is not standardized and regulated due to broad application. This review aims to provide an overview of different decellularization procedures, and we also emphasize the different dECM-derived bioinks present in the current global market and the major clinical outcomes. We have also highlighted an overview of benefits and limitations of different decellularization methods and various characteristic validations of decellularization and dECM-derived bioinks.

Extracellular matrix-derived scaffolds in constructing artificial ovaries for ovarian failure: a systematic methodological review

STUDY QUESTION

What is the current state-of-the-art methodology assessing decellularized extracellular matrix (dECM)-based artificial ovaries for treating ovarian failure?

SUMMARY ANSWER

Preclinical studies have demonstrated that decellularized scaffolds support the growth of ovarian somatic cells and follicles both in vitro and in vivo.

WHAT IS KNOWN ALREADY

Artificial ovaries are a promising approach for rescuing ovarian function. Decellularization has been applied in bioengineering female reproductive tract tissues. However, decellularization targeting the ovary lacks a comprehensive and in-depth understanding.

STUDY DESIGN SIZE DURATION

PubMed, Embase, Web of Science, and the Cochrane Central Register of Controlled Trials were searched from inception until 20 October 2022 to systematically review all studies in which artificial ovaries were constructed using decellularized extracellular matrix scaffolds. The review was performed according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) protocol.

PARTICIPANTS/MATERIALS SETTING METHODS

Two authors selected studies independently based on the eligibility criteria. Studies were included if decellularized scaffolds, regardless of their species origin, were seeded with ovarian cells or follicles. Review articles and meeting papers were removed from the search results, as were articles without decellularized scaffolds or recellularization or decellularization protocols, or control groups or ovarian cells.

MAIN RESULTS AND THE ROLE OF CHANCE

The search returned a total of 754 publications, and 12 papers were eligible for final analysis. The papers were published between 2015 and 2022 and were most frequently reported as coming from Iran. Detailed information on the decellularization procedure, evaluation method, and preclinical study design was extracted. In particular, we concentrated on the type and duration of detergent reagent, DNA and extracellular matrix detection methods, and the main findings on ovarian function. Decellularized tissues derived from humans and experimental animals were reported. Scaffolds loaded with ovarian cells have produced estrogen and progesterone, though with high variability, and have supported the growth of various follicles. Serious complications have not been reported.

LIMITATIONS REASONS FOR CAUTION

A meta-analysis could not be performed. Therefore, only data pooling was conducted. Additionally, the quality of some studies was limited mainly due to incomplete description of methods, which impeded specific data extraction and quality analysis. Several studies that used dECM scaffolds were performed or authored by the same research group with a few modifications, which might have biased our evaluation.

WIDER IMPLICATIONS OF THE FINDINGS

Overall, the decellularization-based artificial ovary is a promising but experimental choice for substituting insufficient ovaries. A generic and comparable standard should be established for the decellularization protocols, quality implementation, and cytotoxicity controls. Currently, decellularized materials are far from being clinically applicable to artificial ovaries.

STUDY FUNDING/COMPETING INTERESTS

This study was funded by the National Natural Science Foundation of China (Nos. 82001498 and 81701438). The authors have no conflicts of interest to declare.

TRIAL REGISTRATION NUMBER

This systematic review is registered with the International Prospective Register of Systematic Reviews (PROSPERO, ID CRD42022338449).

Immediate Prepectoral Breast Reconstruction Using an ADM with Smooth Round Implants – A Prospective Observational Cohort Study

Prepectoral breast reconstruction using acellular dermal matrices (ADMs) is well established and used in candidates for nipple/skin-sparing mastectomies; it is based on many different matrices and a great variability in breast implant selection. We describe our experience and clinical outcomes using Braxon® ADMs and smooth round breast implants. Females aged 18-80 years who underwent mastectomies with immediate prepectoral reconstruction between April 2019 and April 2021 were prospectively included. Complications were classified as mastectomy-related (hematoma, necrosis) or reconstruction-related (seroma, infection, red breast syndrome). Binary logistic regression analysis was performed to assess correlation between complication rate and selected variables, which were analyzed per breast with Kruskal-Wallis H test. Fifty-eight patients (102 breasts) received 45 bilateral and 12 unilateral procedures. Drains collected 485.9 cc [range: 100-1260] and were removed 15.7 days [range: 6-29] postoperatively. We report 41 complications (40.2%): 33 mastectomy-related, 8 reconstruction-related. Reoperation occurred in 14 patients: 7 wound debridement and revisions under local anesthesia; and 7 explantation. Implant loss rate was 6.8%. Mastectomy and reconstruction complications were not correlated with any variable. In conclusion, we found prepectoral reconstruction with Braxon® ADMs and smooth round implants to be associated with acceptable complication rates that are not influenced by any patient- or surgery-related factors. Drainage volume is comparable to other breast implant reconstructive techniques, but drains are left in place for longer.

Chitosan-Based Membranes for Skin Wound Repair in a Dorsal Fold Chamber Rat Model

Frequently, deep partial and full-thickness skin wounds do not spontaneously regenerate. To restore the normal function of skin, epidermal and dermal components have to be supplied to the wound bed by grafting various substrates. Available options are limited and frequently costly. Herein, authors present a possible approach using 3D skin scaffolds capable of mimicking structure and biological functions of the extracellular matrix, providing, in parallel, a good environment for cell attachment, proliferation and differentiation. Low-molecular weight chitosan-based membranes were prepared by freeze-drying and ionizing radiation techniques to be used as skin scaffolds. Poly (vinyl alcohol), PVA, vinyl pyrrolidone, VP, and gelatin from cold water fish were incorporated. Information regarding membranes' physical-chemical properties from SEM analysis, swelling and weight loss, together with biological response through in vitro assays (using Human Caucasian Fetal Foreskin Fibroblast) allowed the selection of an optimized batch of membranes that was used as skin scaffold in a dorsal rat model wound. The in vivo implantation assays (in Wistar rats) resulted in very promising results: (i) healing process faster than control; (ii) good vascularization; (iii) viable new tissues morphologically functional.

Biomaterials for Regenerative Medicine in Italy: Brief State of the Art of the Principal Research Centers

Regenerative medicine is the branch of medicine that effectively uses stem cell therapy and tissue engineering strategies to guide the healing or replacement of damaged tissues or organs. A crucial element is undoubtedly the biomaterial that guides biological events to restore tissue continuity. The polymers, natural or synthetic, find wide application thanks to their great adaptability. In fact, they can be used as principal components, coatings or vehicles to functionalize several biomaterials. There are many leading centers for the research and development of biomaterials in Italy. The aim of this review is to provide an overview of the current state of the art on polymer research for regenerative medicine purposes. The last five years of scientific production of the main Italian research centers has been screened to analyze the current advancement in tissue engineering in order to highlight inputs for the development of novel biomaterials and strategies.

Formulation of Dermal Tissue Matrix Bioink by a Facile Decellularization Method and Process Optimization for 3D Bioprinting toward Translation Research

Decellularized extracellular matrices (ECMs) are being extensively used for tissue engineering purposes and detergents are predominantly used for this. A facile detergent-free decellularization method is developed for dermal matrix and compared it with the most used detergent-based decellularization methods. An optimized, single-step, cost-effective Hypotonic/Hypertonic (H/H) Sodium Chloride (NaCl) solutions-based method is employed to decellularize goat skin that resulted in much higher yield than other methods. The ECM composition, mechanical property, and cytocompatibility are evaluated and compared with other decellularization methods. Furthermore, this H/H-treated decellularized dermal ECM (ddECM) exhibits a residual DNA content of <50 ng mg^-1  of dry tissue. Moreover, 85.64 ± 3.01% of glycosaminoglycans and 65.53 ± 2.9% collagen are retained compared to the native tissue, which is higher than the ddECMs prepared by other methods. The cellular response is superior in ddECM (H/H) than other ddECMs prepared by detergent-based methods. Additionally, a bioink is formulated with the ddECM (H/H), showing good shear thinning and shear recovery properties. Process optimization in terms of print speed, flow rate, and viscosity is done to obtain a bioprinting window for ddECM bioink. The printed constructs with optimized parameters have adequate mechanical and cell adhesive properties and excellent isotropic cellular alignment.

Can Heart Valve Decellularization Be Standardized? A Review of the Parameters Used for the Quality Control of Decellularization Processes

When a tissue or an organ is considered, the attention inevitably falls on the complex and delicate mechanisms regulating the correct interaction of billions of cells that populate it. However, the most critical component for the functionality of specific tissue or organ is not the cell, but the cell-secreted three-dimensional structure known as the extracellular matrix (ECM). Without the presence of an adequate ECM, there would be no optimal support and stimuli for the cellular component to replicate, communicate and interact properly, thus compromising cell dynamics and behaviour and contributing to the loss of tissue-specific cellular phenotype and functions. The limitations of the current bioprosthetic implantable medical devices have led researchers to explore tissue engineering constructs, predominantly using animal tissues as a potentially unlimited source of materials. The high homology of the protein sequences that compose the mammalian ECM, can be exploited to convert a soft animal tissue into a human autologous functional and long-lasting prosthesis ensuring the viability of the cells and maintaining the proper biomechanical function. Decellularization has been shown to be a highly promising technique to generate tissue-specific ECM-derived products for multiple applications, although it might comprise very complex processes that involve the simultaneous use of chemical, biochemical, physical and enzymatic protocols. Several different approaches have been reported in the literature for the treatment of bone, cartilage, adipose, dermal, neural and cardiovascular tissues, as well as skeletal muscle, tendons and gastrointestinal tract matrices. However, most of these reports refer to experimental data. This paper reviews the most common and latest decellularization approaches that have been adopted in cardiovascular tissue engineering. The efficacy of cells removal was specifically reviewed and discussed, together with the parameters that could be used as quality control markers for the evaluation of the effectiveness of decellularization and tissue biocompatibility. The purpose was to provide a panel of parameters that can be shared and taken into consideration by the scientific community to achieve more efficient, comparable, and reliable experimental research results and a faster technology transfer to the market.

Immediate direct-to-implant breast reconstruction with acellular dermal matrix: Evaluation of complications and safety

OBJECTIVE

Immediate direct-to-implant breast reconstruction with acellular dermal matrix (ADM) is the method of choice for many plastic surgeons and patients, but the use of ADM remains a controversial subject in the literature. This study aimed to investigate complications, reconstructive failure and possible risk factors in direct-to-implant breast reconstruction with ADM (primarily Strattice™).

METHODS

We retrospectively examined all patients undergoing immediate direct-to-implant breast reconstruction with ADM, during a five-year period (2014-2019) at a university clinic. Study outcomes were all complications and explantations. Complications were stratified within and after 6 months postoperatively and subcategorized by type of intervention. Explantations were subcategorized into loss of implant or salvage with immediate insertion of a tissue expander, the same or a new implant.

RESULTS

We included 154 patients and 232 breasts. Complications within 6 months per patient included hematoma (4%), seroma (8%), infection (9%), necrosis, wound dehiscence and delayed wound healing (19%). The total complication rate per patient was 34%. Explantation occurred in 20 patients (13%) of which 9 (6% of all) had implant loss. Preoperative radiotherapy was a significant predictor of explantation (adjusted OR 4.9, 95% confidence interval (CI), 1.0-23.5; p = 0.045), and smoking was also associated with risk of explantation, although only borderline significant (adjusted OR 4.0, 95% CI, 1.0-15.8; p = 0.050).

CONCLUSION

This study demonstrates acceptable rates of re-operations and implant loss compared to other studies but highlights the importance of proper patient selection with regards to risk factors to minimize complications.

The First Use of Human-Derived ADM in Prepectoral Direct-to-Implant Breast Reconstruction after Skin-Reducing Mastectomy

INTRODUCTION

Large and ptotic breasts always represented a great reconstructive challenge for plastic surgeons. In order to deal with these patients, we started performing Wise-pattern skin-reducing mastectomies (SRM) followed by direct-to-implant breast reconstructions (DTI-BR) in the prepectoral space where the implants were covered with the autologous adipo-dermal flap and a human acellular dermal matrix called MODA.

MATERIALS AND METHOD

We retrospectively reviewed all patients that underwent Wise-pattern SRM followed by MODA-assisted, prepectoral, DTI-BR between January 2017 and November 2019 at our Institution. Inclusion criteria were large ptotic breast and pinch test >2cm, while exclusion criteria were smoking >10 cigarettes/day, history of prior radiotherapy, patients supposedly requiring breast implants bigger than 550cc or post-mastectomy radiotherapy. Patients' data were collected through their electronic medical records. Both short- and long-term outcomes were reported.

RESULTS

Seventeen patients underwent Wise-pattern SRM followed by MODA-assisted, prepectoral, DTI-BR for a total of twenty-one breast reconstruction and fourteen matching procedures. Mean follow-up was 13.4 months (SD= ±3.67). No major complication was reported. Three (14.3%) reconstructed breasts had minor complications: 2 (9.5%) minimal (<1cm²) wound dehiscence and 1 (4.8%) de-epithelization of the skin at the T junction that were treated conservatively. Drainages gave mean output of 410.59 ml (SD= ±214.83) and were kept in place on average for 8.59 days (SD= ±3.45).

CONCLUSION

Few are the reports in the literature regarding DTI-BR following SRM and even fewer are those where BR was performed in the prepectoral space. Our work demonstrated the safety of prepectoral DTI-BR following SRM in selected patients in accordance with the "conservative reconstruction" principles. Furthermore, we confirmed the reliability of MODA in accordance with previously published works.

LEVEL OF EVIDENCE IV

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 .

The use of human acellular dermal matrices in advanced wound healing and surgical procedures: State of the art

Wound closure after post-traumatic injuries and/or localized at peculiar body sites (head-and-neck, oral cavity, legs) are particularly challenging and can often be delayed due to local and systemic factors. In case of deep wounds and/or hard-to-heal wounds, grafting of dermal acellular matrices (ADM) is often needed. Though a great variety of synthetic and semisynthetic dermal and skin equivalents are available, viable human dermis, is still considered the most physiological alternative to replace the loss of autologous dermis, by acting as a physiological scaffold that add structural support to soft tissues. To date, human ADMs (hADMs) have been employed in the reconstruction of skin defects affecting almost all body sites, ranging from visceral sites to the skin and subcutaneous tissues. This review aims to investigate the use of hADM at different body sites and their peculiar advantages. A literature search was using the search terms "acellular dermal matrices", "dermal regeneration", "advances wound healing", "human acellular dermal matrices surgery". A total of 50 out of 150 papers was included. Based on the current body if evidence, hADMs appear to bring several advantages, such as: protection of deep structures (eg, tendons, bones, cartilage and nerves); stimulation of a functional new dermis (rather than a scar); reduction of wound closure time; control of pain and exudate. Finally, hADMs may represent the best treatment option for hard-to-heal wound not only in terms of efficacy and patient satisfaction bout also in terms of sanitary costs, especially across Europe, where hADMs cannot be commercialized as medical devices.

A New Treatment for the Reconstruction of the Medial Compartment of the Ankle: The Combined Use of Biological Materials

Fractures, especially if articular and periarticular, are frequently associated to functional and clinical disabling outcomes and chronic pain. In particular, the injuries with loss of bone, ligament, and/or tendon tissue in which the full recovery of the wound area is not obtained are the worst anatomical/pathological conditions to heal. In this study, three different biological materials were used as regenerative approaches to rebuild the medial malleolus fracture of the ankle in which loss of bone, ligament, and tendon tissue occur. In particular, the morselized human bone tissue was combined with the human dermis decellularized, both augmented with homologous platelet-rich plasma. The magnetic resonance imaging study with contrast at the follow-up showed a signal compatible with vascularization of the tissue without sign of degeneration. Our new regenerative approach in which different biological materials were combined together showed a good choice of treatment for the reconstruction of not repairable outcome of a fracture.

Sub-muscular Reconstruction after NAC Sparing Mastectomy: Direct to Implant Breast Reconstruction with Human ADM Versus Tissue Expander

BACKGROUND

Nipple areola complex (NAC) sparing mastectomy allows good oncological and aesthetic results. The study compares the results, in terms of self-evaluated satisfaction and symmetry, of direct to implant (DTI) sub-muscular breast reconstruction, with the aid of human acellular dermal matrix (ADM) versus two-stage reconstruction with sub-muscular tissue expander, followed by implant.

MATERIALS AND METHODS

This is a retrospective, observational, single-center, non-randomized, case-control study. Inclusion criteria were: unilateral NAC sparing mastectomy at Forlì Hospital between 2014 and 2018; sub-muscular reconstruction; minimum follow-up of 12 months from the reconstructive stage; no history of radiotherapy. Patients were divided into two groups: group A included patients who underwent DTI breast reconstruction with the aid of human ADM; group B were those who underwent a two-stage reconstruction with tissue expander then implant. We collected data on: (1) Self-evaluated satisfaction by Breast Q questionnaire (scores from 0 to 100). (2) Observer-evaluated symmetry. Bi-dimensional photographs were collected and evaluated by 11 breast surgeons blinded to each other, who assigned a score for symmetry (from 0 to 10). (3) Symmetry of anthropometric measures collected by hand and volume estimated by Breast V application.

RESULTS

Group A included 28 patients; group included B 26 patients. Breast-Q questionnaires reported the following results: satisfaction with breasts in group A 65 ± 12 versus group B 68 ± 14; satisfaction with outcome in group A 88 ± 16 versus group B 93 ± 11; psychosocial well-being in group A 71 ± 20 versus group B 76 ± 17; sexual well-being in group A 63 ± 26 versus group B 60 ± 13; physical well-being in group A 68 ± 15 versus group B 60 ± 12. The average symmetry breast score assigned to group A was 6.9, versus group B 7.2. Regarding the anthropometric measures in group A, the differences between right and left were major to those in group B. Regarding breast volume, the mean difference between right and left in group A was 31.89 cc ± 24.97, whereas in group B was 25.46 cc ± 23.59.

CONCLUSION

Our data show better symmetry and better psychosocial well-being in the two-stage reconstruction, and higher satisfaction with sexual and physical well-being in DTI reconstructions. These aspects should be discussed with the patient while collecting the informed consent.

LEVEL OF EVIDENCE IV

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 .

Tissue-Specific Decellularization Methods: Rationale and Strategies to Achieve Regenerative Compounds

The extracellular matrix (ECM) is a complex network with multiple functions, including specific functions during tissue regeneration. Precisely, the properties of the ECM have been thoroughly used in tissue engineering and regenerative medicine research, aiming to restore the function of damaged or dysfunctional tissues. Tissue decellularization is gaining momentum as a technique to obtain potentially implantable decellularized extracellular matrix (dECM) with well-preserved key components. Interestingly, the tissue-specific dECM is becoming a feasible option to carry out regenerative medicine research, with multiple advantages compared to other approaches. This review provides an overview of the most common methods used to obtain the dECM and summarizes the strategies adopted to decellularize specific tissues, aiming to provide a helpful guide for future research development.

A New Human-Derived Acellular Dermal Matrix for 1-Stage Coverage of Exposed Tendons in the Foot

The closure of wounds associated with soft tissue defects is surgically challenging, frequently requiring extensive plastic surgery and free flaps. The combination of ADM and STSG is an innovative method used to cover such wounds. The human-derived ADMs (H-ADMs) are the most described in the literature but according to European legislations, Companies H-ADMs outside the EC are not allowed to commercialize them in Europe, H-ADMs being “human products” and not “medical devices”, so being ruled by European legislations on transplants. The Skin Bank of the Bufalini Hospital (Cesena, Italy) obtained in 2009 the approval for the production and distribution of the first human cadaver-donor derived ADM from the Italian National Transplant Center and National Health Institute, we called with the Italian acronym M.O.D.A. (Matrice Omologa Dermica Acellulata). We present here the first use of a new H-ADM for treatment of distal lower extremity wounds with exposed tendons managed in one-stage pocedure with STSG. The excellent performance suggests that in cases where autologous tissue is unavailable or undesirable, the use of M.O.D.A. in one-stage procedure represents a promising alternative for covering wounds associated with tendons exposition.

A retrospective review of breast reconstruction outcomes comparing AlloDerm and DermaCELL

Acellular dermal matrix (ADM) has become an accepted and advantageous adjunct to alloplastic breast reconstruction. The increase in demand has led to an upsurge of dermal-based products, both human and animal derived. There are few direct ADM comparative studies, but it is unclear whether there are any differences in complication rates. Our primary objective was to determine whether there is a difference in outcomes between AlloDerm and DermACELL in immediate alloplastic breast reconstruction.

A retrospective chart review of those who underwent immediate alloplastic breast reconstruction from January to December 2016 was performed. This encompassed 64 consecutive patients (95 breasts) with tissue expander or direct-to-implant reconstruction and either AlloDerm or DermACELL ADM. Demographics, particulars of the surgery, additional treatments and complications were all recorded. Differences in seroma, haematoma and infection rates, as well as more serious complications including implant replacement, capsular contracture and failure, were all reviewed.

The groups were comparable in terms of age, BMI and relevant comorbidities. Mastectomy weight and resulting implant volume were higher in the DermACELL group, with volume reaching statistical significance (p = 0.001). With an average follow-up of 18 months, there was no difference in capsular contraction or implant replacement. However, in those who developed capsular contracture in the DermACELL group, more breasts had no history of radiation, which was significant (p = 0.042). Overall, there were no significant differences in complication rates of seroma, haematoma, mastectomy flap necrosis and infection.

The development of a decellularized extracellular matrix-based biomaterial scaffold derived from human foreskin for the purpose of foreskin reconstruction in circumcised males

The circumcision of males is emphatically linked to numerous sexual dysfunctions. Many of the purported benefits do not hold up to the scrutiny of extensive literature surveys. Involuntary circumcision, particularly when not medically warranted, is also associated with many psychological and emotional traumas. Current methods to reconstruct the ablated tissue have significant drawbacks and produce a simple substitute that merely imitates the natural foreskin. Extracellular matrix-based scaffolds have been shown to be highly effective in the repair and regeneration of soft tissues; however, due to the unique nature of the foreskin tissue, commercially available biomaterial scaffolds would yield poor results. Therefore, this study discusses the development and evaluation of a tissue engineering scaffold derived from decellularized human foreskin extracellular matrix for foreskin reconstruction. A chemicophysical decellularization method was applied to human foreskin samples, sourced from consenting adult donors. The resulting foreskin dermal matrices were analyzed for their suitability for tissue engineering purposes, by biological, histological, and mechanical assessment; fresh frozen foreskin was used as a negative control. Sterility of samples at all stages was ensured by microbiological analysis. MTT assay was used to evaluate the absence of viable cells, and histological analysis was used to confirm the maintenance of the extracellular matrix structure and presence/integrity of collagen fibers. Bioactivity was determined by submitting tissue extracts to enzyme-linked immunosorbent assay and quantifying basic fibroblast growth factor content. Mechanical properties of the samples were determined using tensile stress tests. Results found foreskin dermal matrices were devoid of viable cells (p < 0.0001) and the matrix of foreskin dermal matrices was maintained. Basic fibroblast growth factor content doubled within after decellularization (p < 0.0001). Tensile stress tests found no statistically significant differences in the mechanical properties (p < 0.05). These results indicate that the derived foreskin dermal matrix may be suitable in a regenerative approach in the reconstruction of the human foreskin.