Decellularized human dermis to treat massive rotator cuff tears: in vitro evaluations

Exploring polysaccharide and protein-enriched decellularized matrix scaffolds for tendon and ligament repair: A review

Tissue engineering (TE) has become a primary research topic for the treatment of diseased or damaged tendon/ligament (T/L) tissue. T/L injuries pose a severe clinical burden worldwide, necessitating the development of effective strategies for T/L repair and tissue regeneration. TE has emerged as a promising strategy for restoring T/L function using decellularized extracellular matrix (dECM)-based scaffolds. dECM scaffolds have gained significant prominence because of their native structure, relatively high bioactivity, low immunogenicity, and ability to function as scaffolds for cell attachment, proliferation, and differentiation, which are difficult to imitate using synthetic materials. Here, we review the recent advances and possible future prospects for the advancement of dECM scaffolds for T/L tissue regeneration. We focus on crucial scaffold properties and functions, as well as various engineering strategies employed for biomaterial design in T/L regeneration. dECM provides both the physical and mechanical microenvironments required by cells to survive and proliferate. Various decellularization methods and sources of allogeneic and xenogeneic dECM in T/L repair and regeneration are critically discussed. Additionally, dECM hydrogels, bio-inks in 3D bioprinting, and nanofibers are briefly explored. Understanding the opportunities and challenges associated with dECM-based scaffold development is crucial for advancing T/L repairs in tissue engineering and regenerative medicine.

Advances in Regenerative Sports Medicine Research

Regenerative sports medicine aims to address sports and aging-related conditions in the locomotor system using techniques that induce tissue regeneration. It also involves the treatment of meniscus and ligament injuries in the knee, Achilles’ tendon ruptures, rotator cuff tears, and cartilage and bone defects in various joints, as well as the regeneration of tendon–bone and cartilage–bone interfaces. There has been considerable progress in this field in recent years, resulting in promising steps toward the development of improved treatments as well as the identification of conundrums that require further targeted research. In this review the regeneration techniques currently considered optimal for each area of regenerative sports medicine have been reviewed and the time required for feasible clinical translation has been assessed. This review also provides insights into the direction of future efforts to minimize the gap between basic research and clinical applications.

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 .

Biomaterials strategies to balance inflammation and tenogenesis for tendon repair

Adult tendon tissue demonstrates a limited regenerative capacity, and the natural repair process leaves fibrotic scar tissue with inferior mechanical properties. Surgical treatment is insufficient to provide the mechanical, structural, and biochemical environment necessary to restore functional tissue. While numerous strategies including biodegradable scaffolds, bioactive factor delivery, and cell-based therapies have been investigated, most studies have focused exclusively on either suppressing inflammation or promoting tenogenesis, which includes tenocyte proliferation, ECM production, and tissue formation. New biomaterials-based approaches represent an opportunity to more effectively balance the two processes and improve regenerative outcomes from tendon injuries. Biomaterials applications that have been explored for tendon regeneration include formation of biodegradable scaffolds presenting topographical, mechanical, and/or immunomodulatory cues conducive to tendon repair; delivery of immunomodulatory or tenogenic biomolecules; and delivery of therapeutic cells such as tenocytes and stem cells. In this review, we provide the biological context for the challenges in tendon repair, discuss biomaterials approaches to modulate the immune and regenerative environment during the healing process, and consider the future development of comprehensive biomaterials-based strategies that can better restore the function of injured tendon. STATEMENT OF SIGNIFICANCE: Current strategies for tendon repair focus on suppressing inflammation or enhancing tenogenesis. Evidence indicates that regulated inflammation is beneficial to tendon healing and that excessive tissue remodeling can cause fibrosis. Thus, it is necessary to adopt an approach that balances the benefits of regulated inflammation and tenogenesis. By reviewing potential treatments involving biodegradable scaffolds, biological cues, and therapeutic cells, we contrast how each strategy promotes or suppresses specific repair steps to improve the healing outcome, and highlight the advantages of a comprehensive approach that facilitates the clearance of necrotic tissue and recruitment of cells during the inflammatory stage, followed by ECM synthesis and organization in the proliferative and remodeling stages with the goal of restoring function to the tendon.

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.

Anterior Capsule Reconstruction Versus Pectoralis Major Transfer for Irreparable Subscapularis Tears Involving the Anterior Capsule: A Comparative Biomechanical Cadaveric Study

PURPOSE

To compare the biomechanical effectiveness of human dermal allograft (HDA) anterior capsular reconstruction (ACR) and pectoralis major tendon transfer (PMTT) for treating irreparable subscapularis tears with capsular insufficiency in human cadaver shoulders.

METHODS

Glenohumeral rotational range of motion and translation were measured in 6 cadaveric shoulders under the following 5 conditions: intact, deficient subscapularis/anterior capsule, ACR using HDA, HDA ACR with concomitant PMTT, and PMTT alone.

RESULTS

The deficient subscapularis/anterior capsule condition significantly increased external and total rotational range of motion at 0° (P < .001, P < .001) and 30° (P = .005, P = .002) abduction as well as anterior-inferior translation (P ≤ .001 to .03). HDA ACR, both with and without PMTT, restored anterior-inferior stability to that of the intact condition; however, PMTT alone did not restore anterior-inferior translation or rotational range of motion.

CONCLUSIONS

HDA ACR for treating irreparable subscapularis tears with capsular insufficiency restored anterior-inferior glenohumeral translation and rotational range of motion at time 0 in human cadaver shoulders.

CLINICAL RELEVANCE

Anterior capsule reconstruction may be a viable option for treating massive irreparable subscapularis tears with capsular insufficiency.

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

INTRODUCTION

The introduction of acellular dermal matrices (ADMs) contributed to the growing diffusion of direct-to-implant breast reconstruction (DTI-BR) following mastectomy for breast cancer. According to specific legislations, European specialists could not benefit from the use of human-derived ADMs, even though most evidence in the literature are available for this kind of device, showed optimal outcomes in breast reconstruction. The Skin Bank of the Bufalini Hospital (Cesena, Italy) obtained in 2009 the approval for the production and distribution of a new human cadaver-donor-derived ADM (named with the Italian acronym, MODA, for matrice omologa dermica acellulata) from the Italian National Transplant Center and National Health Institute. We report preliminary results of MODA application in direct-to-implant breast reconstruction following nipple-areola complex (NAC)-sparing mastectomy for breast cancer treatment.

MATERIALS AND METHODS

We prospectively enrolled all women undergoing NAC-sparing mastectomy for breast cancer and DTI-BR in our breast surgical unit from June 2015 to January 2017. We enrolled a selected population without previous chest wall irradiation, not being heavy tobacco smokers or diabetic, with a BMI < 30 kg/m² and requiring less than 550 cc silicone implants. We assessed short-term outcomes, defined as postoperative complications presenting in the first 30 postoperative days and long-term outcomes at 6 and 12 months.

RESULTS

From June 2015 to January 2017, we treated 56 breasts. At a mean follow-up of 14 months, we observed only two minor complications described as limited wound dehiscences, conservatively managed with complete resolution without implant exposure or re-intervention.

CONCLUSIONS

Our preliminary results show very good performance of MODA in direct-to-implant breast reconstruction following NAC-sparing mastectomy for breast cancer treatment. This is particularly relevant for the European market, where no other human-derived devices are available for breast reconstruction due to regulatory restrictions.

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 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.

Augmentation of Rotator Cuff Repair With Soft Tissue Scaffolds

Background

Tears of the rotator cuff are one of the most common tendon disorders. Treatment often includes surgical repair, but the rate of failure to gain or maintain healing has been reported to be as high as 94%. This has been substantially attributed to the inadequate capacity of tendon to heal once damaged, particularly to bone at the enthesis. A number of strategies have been developed to improve tendon-bone healing, tendon-tendon healing, and tendon regeneration. Scaffolds have received considerable attention for replacement, reconstruction, or reinforcement of tendon defects but may not possess situation-specific or durable mechanical and biological characteristics.

Purpose

To provide an overview of the biology of tendon-bone healing and the current scaffolds used to augment rotator cuff repairs.

Study Design

Systematic review; Level of evidence, 4.

Methods

A preliminary literature search of MEDLINE and Embase databases was performed using the terms rotator cuff scaffolds, rotator cuff augmentation, allografts for rotator cuff repair, xenografts for rotator cuff repair, and synthetic grafts for rotator cuff repair.

Results

The search identified 438 unique articles. Of these, 214 articles were irrelevant to the topic and were therefore excluded. This left a total of 224 studies that were suitable for analysis.

Conclusion

A number of novel biomaterials have been developed into biologically and mechanically favorable scaffolds. Few clinical trials have examined their effect on tendon-bone healing in well-designed, long-term follow-up studies with appropriate control groups. While there is still considerable work to be done before scaffolds are introduced into routine clinical practice, there does appear to be a clear indication for their use as an interpositional graft for large and massive retracted rotator cuff tears and when repairing a poor-quality degenerative tendon.

In vitro tenocyte metabolism in aging and oestrogen deficiency

Little is known about tendons and tenocyte biological behaviour during aging and, especially, oestrogen deficiency. The aim of this study was to evaluate in vitro the proliferation and metabolism of tenocytes isolated from the Achilles tendons of ovariectomised (OVX), middle-aged (OLD) and young (YOUNG) rats. An in vitro model of micro-wound healing was also used to assess age and oestrogen deficiency differences in tendon healing. In standard culture condition, OLD and OVX tenocytes showed a significantly lower proliferation rate, collagen I, aggrecan and elastin than YOUNG ones. In OVX group, fibronectin and elastin significantly decreased in comparison to YOUNG and OLD groups, respectively, whereas vascular endothelial growth factor and metalloproteinases-13 increased than those of both YOUNG and OLD groups. In the micro-wound healing model, tenocytes from both OVX and OLD showed a significantly lower healing rate, proliferation rate, collagen I and nitrix oxide in comparison to YOUNG. OVX elastin value was significantly lower than YOUNG one and OVX healing rate and cell migration speed, proliferation rate and fibronectin results were lower, whereas collagen III and metalloproteinase-13 higher in comparison to both YOUNG and OLD groups. These results highlighted how aging and, more significantly, oestrogen deficiency negatively affect tendon metabolism and healing. Our work improves the body of knowledge on the effects of senescence and oestrogen deficiency on tenocyte behaviour and allows further studies to find solution for the prevention of tendon injuries in aging and menopause.

Response of human chondrocytes and mesenchymal stromal cells to a decellularized human dermis

Background

Although progress has been made in the treatment of articular cartilage lesions, they are still a major challenge because current techniques do not provide satisfactory long-term outcomes. Tissue engineering and the use of functional biomaterials might be an alternative regenerative strategy and fulfill clinical needs. Decellularized extracellular matrices have generated interest as functional biologic scaffolds, but there are few studies on cartilage regeneration. The aim of this study was to evaluate in vitro the biological influence of a newly developed decellularized human dermal extracellular matrix on two human primary cultures.

Methods

Normal human articular chondrocytes (NHAC-kn) and human mesenchymal stromal cells (hMSC) from healthy donors were seeded in polystyrene wells as controls (CTR), and on decellularized human dermis batches (HDM_derm) for 7 and 14 days. Cellular proliferation and differentiation, and anabolic and catabolic synthetic activity were quantified at each experimental time. Histology and scanning electron microscopy were used to evaluate morphology and ultrastructure.

Results

Both cell cultures had a similar proliferation rate that increased significantly (p < 0.0005) at 14 days. In comparison with CTR, at 14 days NHAC-kn enhanced procollagen type II (CPII, p < 0.05) and aggrecan synthesis (p < 0.0005), whereas hMSC significantly enhanced aggrecan synthesis (p < 0.0005) and transforming growth factor-beta1 release (TGF-β1, p < 0.0005) at both experimental times. Neither inflammatory stimulus nor catabolic activity induction was observed. By comparing data of the two primary cells, NHAC-kn synthesized significantly more CPII than did hMSC at both experimental times (p < 0.005), whereas hMSC synthesized more aggrecan at 7 days (p < 0.005) and TGF-β1 at both experimental times than did NHAC-kn (p < 0.005).

Conclusions

The results obtained showed that in in vitro conditions HDM_derm behaves as a suitable scaffold for the growth of both well-differentiated chondrocytes and undifferentiated mesenchymal cells, thus ensuring a biocompatible and bioactive substrate. Further studies are mandatory to test the use of HDM_derm with tissue engineering to assess its therapeutic and functional effectiveness in cartilage regeneration.

Decellularized tendon extracellular matrix-a valuable approach for tendon reconstruction?

Tendon healing is generally a time-consuming process and often leads to a functionally altered reparative tissue. Using degradable scaffolds for tendon reconstruction still remains a compromise in view of the required high mechanical strength of tendons. Regenerative approaches based on natural decellularized allo- or xenogenic tendon extracellular matrix (ECM) have recently started to attract interest. This ECM combines the advantages of its intrinsic mechanical competence with that of providing tenogenic stimuli for immigrating cells mediated, for example, by the growth factors and other mediators entrapped within the natural ECM. A major restriction for their therapeutic application is the mainly cell-associated immunogenicity of xenogenic or allogenic tissues and, in the case of allogenic tissues, also the risk of disease transmission. A survey of approaches for tendon reconstruction using cell-free tendon ECM is presented here, whereby the problems associated with the decellularization procedures, the success of various recellularization strategies, and the applicable cell types will be thoroughly discussed. Encouraging in vivo results using cell-free ECM, as, for instance, in rabbit models, have already been reported. However, in comparison to native tendon, cells remain mostly inhomogeneously distributed in the reseeded ECM and do not align. Hence, future work should focus on the optimization of tendon ECM decellularization and recolonization strategies to restore tendon functionality.