Characterization of a new decellularized bovine pericardial biological mesh: Structural and mechanical properties

Crosslinking strategies of decellularized extracellular matrix in tissue regeneration

By removing the immunogenic cellular components through various decellularization methods, decellularized extracellular matrix (dECM) is considered a promising material in the field of tissue engineering and regenerative medicine with highly preserved physicochemical properties and superior biocompatibility. However, decellularization treatment can lead to some loss of structural integrity, mechanical strength, degradation stability, and biological performance of dECM biomaterials. Therefore, physical and chemical crosslinking methods are preferred to restore or even improve the biomechanical properties, stability, and bioactivity, and to achieve a delicate balance between degradation of the implanted biomaterial and regeneration of the host tissue. This review provides an overview of dECM biomaterials, and describes and compares the mechanisms and characteristics of commonly used crosslinking methods for dECM, with a focus on the potential applications of versatile dECM-based biomaterials derived from skin, cardiac tissues (pericardium, heart valves, myocardial tissue), blood vessels, liver, and kidney, modified with different chemical crosslinking reagents, in tissue and organ regeneration.

A High-biocompatibility Interface for the Breast Implant: First Report of a Novel Biological Matrix-assisted Technique in Aesthetic Revision Surgery

Development of human-compatible tissues is an active field of research that is leading to the production of optimized biological scaffolds to support regenerative medicine. Xenogenic acellular matrices are known to have strongly influenced the field of breast surgery, playing an integral role in wound healing and in preventing the foreign body reaction to silicone implants. Here, we present our experience in using a biological matrix for aesthetic revision surgery with malposition and severe capsular contracture. Revisions were performed using the new MASQUE equine acellular-pericardium-matrix (APM) as an anterior cover for the synthetic prosthesis. Acting as an internal support, the thin APM layer provides a biological and biocompatible interface between the synthetic implant and living tissues, exerting a protective function against fibrotic responses and capsular contracture. The role of an APM in matrix-assisted mammoplasty has yet to be fully established. Our early experience of APM-assisted aesthetic revision surgery shows promising results, laying the foundations for equine biological matrices as a valid tool for the management of capsular contracture-susceptible patients.

Decellularized Scaffolds of Nopal (Opuntia Ficus-indica) for Bioengineering in Regenerative Dentistry

Opuntia Ficus-indica, or nopal, is traditionally used for its medicinal properties in Mexico. This study aims to decellularize and characterize nopal (Opuntia Ficus-indica) scaffolds, assess their degradation and the proliferation of hDPSC, and determine potential pro-inflammatory effects by assessing the expression of cyclooxygenase 1 and 2 (COX-1 and 2). The scaffolds were decellularized using a 0.5% sodium dodecyl sulfate (SDS) solution and confirmed by color, optical microscopy, and SEM. The degradation rates and mechanical properties of the scaffolds were determined by weight and solution absorbances using trypsin and PBS and tensile strength testing. Human dental pulp stem cells (hDPSCs) primary cells were used for scaffold-cell interaction and proliferation assays, as well as an MTT assay to determine proliferation. Proinflammatory protein expression of COX-I and -II was discovered by Western blot assay, and the cultures were induced into a pro-inflammatory state with interleukin 1-β. The nopal scaffolds exhibited a porous structure with an average pore size of 252 ± 77 μm. The decellularized scaffolds showed a 57% reduction in weight loss during hydrolytic degradation and a 70% reduction during enzymatic degradation. There was no difference in tensile strengths between native and decellularized scaffolds (12.5 ± 1 and 11.8 ± 0.5 MPa). Furthermore, hDPSCs showed a significant increase in cell viability of 95% and 106% at 168 h for native and decellularized scaffolds, respectively. The combination of the scaffold and hDPSCs did not cause an increase in the expression of COX-1 and COX-2 proteins. However, when the combination was exposed to IL-1β, there was an increase in the expression of COX-2. This study demonstrates the potential application of nopal scaffolds in tissue engineering and regenerative medicine or dentistry, owing to their structural characteristics, degradation properties, mechanical properties, ability to induce cell proliferation, and lack of enhancement of pro-inflammatory cytokines.

Molecular dynamics simulations and in vitro studies of hybrid decellularized leaf-peptide-polypyrrole composites for potential tissue engineering applications

Tissue engineering (TE) aims to repair and regenerate damaged tissue by an assimilation of optimal combination of cells specific to the tissue with an appropriate biomaterial. In this work, a new biomaterial for potential cardiac TE applications was developed by utilizing a combination of in silico studies and in vitro experiments. Molecular dynamics (MD) simulations for the formation of the novel composite prepared from the decellularized leaf components cellulose and pectin along with the VEGF derived peptide (NYLTHRQ) and polypyrrole (PPy) was carried out to assess self-assembly, mechanical properties, and interactions with integrin and NPR-C receptors which are commonly found in cells of cardiac tissue. Results of molecular dynamics simulations indicated the successful formation of stable assemblies. MD simulations also revealed that the scaffold successfully interacted with integrin and NPR-C receptors. As a proof of concept, beet leaves were decellularized (DC) and cross-linked with NYLTHRQ and PPy using layer-by-layer assembly. Decellularization (DC) was confirmed by DNA and protein quantification. Incorporation of the NYLTHRQ peptide and polypyrrole was confirmed by FTIR spectroscopy and SEM imaging. The DC-NYLTHRQ-PPy scaffold was seeded with co-cultured cardiomyocytes and vascular smooth muscle cells. The scaffold promoted cell proliferation and adhesion. Actin and Troponin T immunofluorescence staining showed the presence of these critical cardiomyocyte markers. Thus, for the first time we have developed a decellularized leaf-peptide-PPy composite scaffold by a combination of in silico studies and laboratory analyses that may have potential applications in cardiac TE.Communicated by Ramaswamy H. Sarma.

Decellularization in Tissue Engineering and Regenerative Medicine: Evaluation, Modification, and Application Methods

Reproduction of different tissues using scaffolds and materials is a major element in regenerative medicine. The regeneration of whole organs with decellularized extracellular matrix (dECM) has remained a goal despite the use of these materials for different purposes. Recently, decellularization techniques have been widely used in producing scaffolds that are appropriate for regenerating damaged organs and may be able to overcome the shortage of donor organs. Decellularized ECM offers several advantages over synthetic compounds, including the preserved natural microenvironment features. Different decellularization methods have been developed, each of which is appropriate for removing cells from specific tissues under certain conditions. A variety of methods have been advanced for evaluating the decellularization process in terms of cell removal efficiency, tissue ultrastructure preservation, toxicity, biocompatibility, biodegradability, and mechanical resistance in order to enhance the efficacy of decellularization methods. Modification techniques improve the characteristics of decellularized scaffolds, making them available for the regeneration of damaged tissues. Moreover, modification of scaffolds makes them appropriate options for drug delivery, disease modeling, and improving stem cells growth and proliferation. However, considering different challenges in the way of decellularization methods and application of decellularized scaffolds, this field is constantly developing and progressively moving forward. This review has outlined recent decellularization and sterilization strategies, evaluation tests for efficient decellularization, materials processing, application, and challenges and future outlooks of decellularization in regenerative medicine and tissue engineering.

4-Arm PEG-Functionalized Decellularized Pericardium for Effective Prevention of Postoperative Adhesion in Cardiac Surgery

Postoperative adhesions are a very common and serious complication in cardiac surgery, and the development of an effective anti-adhesion membrane showing resistance to the physical stimulus generated by the pulsation of the heart is desirable. In this study, an anti-adhesion material was developed through amine coupling between decellularized bovine pericardia (dBPCs) and 4-arm poly(ethylene glycol) succinimidyl glutarate (4-arm PEG-NHS) for the postoperative care of cardiac surgical patients. The efficacy of the 4-arm PEG-functionalized dBPCs in the prevention of adhesions after cardiac surgery was investigated in a rabbit heart adhesion model. The dBPCs meet the requirements for biocompatibility, flexibility, and sufficient suturable strength, and the 4-arm PEG moieties provide an anti-adhesion effect by the high excluded volume interactions of the PEG chains with proteins. The 4-arm PEG-functionalized dBPCs had a significantly greater anti-adhesion effect than the other materials tested and showed re-establishment of the mesothelial monolayer. These results suggested that the 4-arm PEG-functionalized dBPCs are a favorable material for an anti-adhesion membrane.

Transcatheter aortic valve implantation in patients with unruptured aortic root pseudoaneurysm: an observational study

AIMS

Unruptured aortic root pseudoaneurysm (UARP) is a rare complication of aortic valve endocarditis. Infectious spread to the valvular annulus or myocardium can cause septic complications that manifest as wall thickening, and spontaneous abscess drainage leads to pseudoaneurysm formation. We report the first patient series in which transcatheter aortic valve implantation (TAVI) using a single valve-resolved aortic valvulopathy associated with UARP was performed.

METHODS

At our center, from December 2017 to October 2019, 138 patients underwent TAVI for aortic valve stenosis and/or regurgitation, 20 of whom (12 female patients, 8 male patients) had associated incidental UARP and were considered as our study population. The average age of these patients was 76.9 ± 5.2 years. All patients were assessed using preprocedural and postprocedural multimodality imaging, including transthoracic echocardiography, transesophageal echocardiography, and cardiac computed tomography angiography (CCTA).

RESULTS

In all cases, the final angiographic examination showed correct valve positioning with complete coverage of the false aneurysm. Post-TAVI CCTA showed presence of total or subtotal UARP thrombosis. The mean follow-up period was 17.5 months (12-23 months). During follow-up, imaging showed normal prosthetic valve function, no significant leakage (trace or mild), and complete UARP exclusion in all patients, without any complications.

CONCLUSION

In conclusion, percutaneous valve positioning can simultaneously solve pseudoaneurysm complications by excluding the sac and promoting thrombosis.

Recellularization of Native Tissue Derived Acellular Scaffolds with Mesenchymal Stem Cells

The functionalization of decellularized scaffolds is still challenging because of the recellularization-related limitations, including the finding of the most optimal kind of cell(s) and the best way to control their distribution within the scaffolds to generate native mimicking tissues. That is why researchers have been encouraged to study stem cells, in particular, mesenchymal stem cells (MSCs), as alternative cells to repopulate and functionalize the scaffolds properly. MSCs could be obtained from various sources and have therapeutic effects on a wide range of inflammatory/degenerative diseases. Therefore, in this mini-review, we will discuss the benefits using of MSCs for recellularization, the factors affecting their efficiency, and the drawbacks that may need to be overcome to generate bioengineered transplantable organs.

Feasibility and Oncological Safety of Axillary Reverse Mapping in Patients With Locally Advanced Breast Cancer and Partial Response After Neoadjuvant Chemotherapy

BACKGROUND/AIM

Axillary reverse mapping (ARM) aims to identify and preserve arm drainage in order to prevent lymphedema following axillary lymph node dissection. Oncological-safety and feasibility are still debated, especially in patients with locally-advanced breast cancer (LABC). We report the first case of the AXMAP 1.0 study performed in our Institution.

PATIENTS AND METHODS

A 52-year-old patient with a triple-negative LABC and partial response to neoadjuvant chemotherapy underwent axillary lymph-node dissection using fluorescence ARM.

RESULTS

Two lymph-nodes draining the ipsilateral upper arm were identified and were not preserved due to suspicion of malignancy. Pathological examination confirmed the presence of malignancy in both lymph nodes.

CONCLUSION

Further studies should be designed in order to validate the oncological safety of this technique, especially in patients with LABC requiring neoadjuvant chemotherapy.

Extremely Advanced Breast Cancer Presentation: Possible Effect of Coronavirus Pandemic Anxiety

BACKGROUND/AIM

Corona virus infection dramatically spread worldwide during 2020 and extraordinary restrictions have been implemented in order to reduce viral transmission. These measures compelled a complete restructuring of the health system, including temporary cancer screening suspension and a significant slow-down in cancer diagnoses and treatments.

CASE REPORT

We report five cases of extremely advanced breast cancer referred to our Department amid the COVID-19 pandemic. These patients exhibited a poor prognosis or worse quality of life due to their oncological disease.

CONCLUSION

In our opinion, both the slow-down of diagnosis and treatment of oncological disease and anxiety over COVID-19 influenced this presentation. Moreover, other patients were unable to receive palliative care. Hopefully, these cases will not develop into extremely advanced-stage disease, and we will be able to provide at least the necessary palliative care.

The effect of Scrophularia striata on cell attachment and biocompatibility of decellularized bovine pericardia

Since using tissue transplantation has faced limitations all over the world, regenerative medicine has introduced decellularized tissues as natural scaffolds and researchers are trying to improve their efficiency and function. In this study, to increase cell attachment and ultimately cell proliferation on decellularized bovine pericardia, scrophularia striata extract was used. Scrophularia striata is an Iranian traditional medicinal plant. For this aim after decellularization of bovine pericardium and analysis of its morphology, it was incubated in scrophularia striata solution. Next, isolated human adipose-derived mesenchymal stem cells were cultured on the tissue. Finally, MTT assay, nitric oxide assay, and scanning electron microscopy observation were performed. MTT showed an increase in cell survival after treating the tissue with the plant extract after 48 h in a dose dependent manner significantly. The survival of cells in 0.5%, 2.5%, and 5% groups was about 5, 10 and 15 folds higher in comparison to control groups, respectively. Additionally, nitric oxide secretion in 2.5% and 5% samples was three and five folds higher than that in control group, respectively. Moreover, SEM observation indicated an impressive and dose-dependent effect of using Scrophularia striata on tissue biocompatibility. The results of this study showed that using Scrophularia striata increased cell viability and cell attachment on decellularized pericardia which could pave the way for the use of natural extracts of medicinal plants to reduce unwanted effects and make desired changes in decellularized tissues.

Covalent functionalization of decellularized tissues accelerates endothelialization

In the field of tissue regeneration, the lack of a stable endothelial lining may affect the hemocompatibility of both synthetic and biological replacements. These drawbacks might be prevented by specific biomaterial functionalization to induce selective endothelial cell (EC) adhesion. Decellularized bovine pericardia and porcine aortas were selectively functionalized with a REDV tetrapeptide at 10⁻⁵ M and 10⁻⁶ M working concentrations. The scaffold-bound peptide was quantified and REDV potential EC adhesion enhancement was evaluated in vitro by static seeding of human umbilical vein ECs. The viable cells and MTS production were statistically higher in functionalized tissues than in control. Scaffold histoarchitecture, geometrical features, and mechanical properties were unaffected by peptide anchoring. The selective immobilization of REDV was effective in accelerating ECs adhesion while promoting proliferation in functionalized decellularized tissues intended for blood-contacting applications.

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Covalent functionalization of the decellularized tissues with REDV peptide accelerates endothelialization.

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New covalent grafting method not inducing collagen cross-linking.

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Measurements through two photon miscroscopy allow the quantification of biological matrix bound peptide.

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The decellularized tissues can be changed by chemical procedures to promote specific cellular behaviour with ECM preservation.

Photooxidation crosslinking to recover residual stress in decellularized blood vessel

Decellularization method based on trypsin-digestion is widely used to construct small diameter vascular grafts. However, this method will reduce the opening angle of the blood vessel and result in the reduction of residual stress. Residual stress reduced has an adverse effect on the compliance and permeability of small diameter vascular grafts. To improve the situation, acellular blood vessels were treated with glutaraldehyde and photooxidation crosslinking respectively, and the changes of opening angle, circumferential residual strain of native blood vessels, decellularized arteries and crosslinked blood vessels were measured by means of histological examination, scanning electron microscopy (SEM) and transmission electron microscopy (TEM) in this study. The opening angle of decellularized arteries significantly restored after photooxidation crosslinking (P = 0.0216), while that of glutaraldehyde crosslinking blood vessels reduced. The elastic fibers inside the blood vessels became densely rearranged after photooxidation crosslinking. The results of finite element simulation showed that the residual stress increased with the increase of opening angle. In this study, we found at the first time that photooxidation crosslinking method could significantly increase the residual stress of decellularized vessels, which provides biomechanical support for the development of new biomaterials of vascular grafts.

Mapping of bovine pericardium to enable a standardized acquirement of material for medical implants

OBJECTIVES

Bovine pericardium - native, fixed as well as decellularized - is one of the most common implant materials in modern cardiovascular surgery. Although used in everyday procedures, there are no recommendations in regard to which part of the pericardium to prefer. It was the aim of this study, to identify areas of the pericardium with consistent properties and high durability.

METHODS

Fresh bovine pericardia were collected from a local slaughterhouse. The native pericardia were analyzed at 140 spots in regard to thickness and fiber orientation. Based on these results, five promising areas were selected for further evaluation. The pericardia were decellularized with detergents (0.5% sodiumdesoxycholate/0.5% sodiumdodecylsulfate) and subsequently incubated in DNAse. The two investigation groups native und DC consisted of 20 samples each. The efficiency of the decellularization was evaluated by DNA quantification, as well as DAPI and H&E staining. Biomechanical properties were determined using uniaxial tensile tests. To evaluate the microstructure, scanning electron microscopy, Picrosirius Red- and Movat's Pentachrome staining were utilized. To assess the long-term durability, patches were tested in a high-cycle system for a duration equaling the stress of three months in-vivo. Commercially available, fixed pericardium patches served as control group.

RESULTS

Only a limited part of the pericardium showed a homogenous and usable thickness. The decellularization removed all cell nuclei, proven by negative DAPI and H&E staining, and also significantly reduced the DNA amount by 84%. The mechanical testing revealed that two investigated areas had an inconsistent tensile strength. Microscopical observations showed that the integrity of the extracellular matrix did not suffer by the decellularization procedure. During the long-term testing, most of the pericardia slowly lost tautness, though none of them got measurably damaged. Especially one area showed no decline of tensile strength after durability testing at all. Decellularized patches and fixed patches achieved comparable results in mechanical testing and microscopical evaluation after the durability testing.

CONCLUSION

We could clearly document significant, location-based differences within single pericardia. Only one area showed consistent properties and a high durability. We highly recommend taking this into account for future implant material selections.

Case Report: Early Breast Cancer Recurrence Mimicking BIA-ALCL in a Patient With Multiple Breast Procedures

Breast reconstruction plays a fundamental role in the therapeutic process of breast cancer treatment and breast implants represents the leading breast reconstruction strategy. Breast Implant Associated-Anaplastic Large Cell Lymphoma (BIA-ALCL), locoregional recurrence in the skin flap, and skin flap necrosis are well-known complications following mastectomy and immediate breast reconstruction (IBR). We report a case of locoregional cancer recurrence in the mastectomy flap mimicking BIA-ALCL, in a patient who underwent 6 breast procedures in four facilities across 15 years including immediate breast reconstruction with macrotextured breast implants. Despite the rate and onset of the disease, clinicians should be aware of BIA-ALCL. Due to the risk of false negative results of fine needle aspiration, clinical suspicion of BIA-ALCL should drive clinicians' choices, aside from cytological results. In the present case, surgical capsulectomy of the abnormal periprosthesic tissue revealed locoregional recurrence.

A Review of Zein as a Potential Biopolymer for Tissue Engineering and Nanotechnological Applications

Tissue engineering (TE) is one of the most challenging fields of research since it provides current alternative protocols and materials for the regeneration of damaged tissue. The success of TE has been mainly related to the right selection of nano-sized biocompatible materials for the development of matrixes, which can display excellent anatomical structure, functionality, mechanical properties, and histocompatibility. Today, the research community has paid particular attention to zein as a potential biomaterial for TE applications and nanotechnological approaches. Considering the properties of zein and the advances in the field, there is a need to reviewing the current state of the art of using this natural origin material for TE and nanotechnological applications. Therefore, the goal of this review paper is to elucidate the latest (over the last five years) applications and development works in the field, including TE, encapsulations of drugs, food, pesticides and bandaging for external wounds. In particular, attention has been focused on studies proving new breakthroughs and findings. Also, a complete background of zein’s properties and features are addressed.

Lockdown of Breast Cancer Screening for COVID-19: Possible Scenario

BACKGROUND/AIM

Coronavirus disease is spreading worldwide. Due to fast transmission and high fatality rate drastic emergency restrictions were issued. During the lockdown, only urgent medical services are guaranteed. All non-urgent services, as breast cancer (BC) screening, are temporarily suspended. The potential of breast cancer screening programs in increasing the survival rate and decreasing the mortality rate has been widely confirmed. Suspension could lead to worse outcomes for breast cancer patients. Our study aimed to analyse the data and provide estimates regarding the temporary BC screening suspension.

PATIENTS AND METHODS

Data regarding breast cancer and respective screening programs were achieved through literature research and analysis.

RESULTS

Considering three different scenarios with respect to the lockdown's impact on breast cancer screening, we estimate that approximately 10,000 patients could have a missed diagnosis during these 3 months. Considering a 6-month period, as suggested by the Imperial college model, the number of patients who will not receive a diagnosis will rise to 16,000.

CONCLUSION

Breast cancer screening should be resumed as soon as possible in order to avoid further breast cancer missed diagnosis and reduce the impact of delayed diagnosis.

Extracellular matrix-derived biomaterials in engineering cell function

Extracellular matrix (ECM) derived components are emerging sources for the engineering of biomaterials that are capable of inducing desirable cell-specific responses. This review explores the use of biomaterials derived from naturally occurring ECM proteins and their derivatives in approaches that aim to regulate cell function. Biomaterials addressed are grouped into six categories: purified single ECM proteins, combinations of purified ECM proteins, cell-derived ECM, tissue-derived ECM, diseased and modified ECM, and ECM-polymer coupled biomaterials. Purified ECM proteins serve as a material coating for enhanced cell adhesion and biocompatibility. Cell-derived and tissue-derived ECM, generated by cell isolation and decellularization technologies, can capture the native state of the ECM environment and guide cell migration and alignment patterns as well as stem cell differentiation. We focus primarily on recent advances in the fields of soft tissue, cardiac, and dermal repair, and explore the utilization of ECM proteins as biomaterials to engineer cell responses.

Feasibility study on equine acellular pericardium matrix (APM): A new tool for breast reconstruction

The advent of acellular dermal matrix (ADM) for lower pole coverage allows immediate reconstructions with improved aesthetic outcomes and faster recovery. This study describes for the first time, the use of a new acellular pericardium matrix (APM) in implant-based breast reconstruction and characterises its safety profile. Equity is a membrane with a natural cross-linked structure with many of the properties of ADMs, but improved resistance and reduced thickness. A retrospective data collection of all Equity APM reconstructions was conducted at two Italian hospital centres with substantial experience using biomaterials. Between May 2013 and October 2018, a total of 63 APM-assisted breast reconstructions were performed in 55 women. The reconstructed breasts were small to medium and the mean implant weight was 285 g, ranging from 145 g to 685 g. Two patients were previously irradiated while seven received post-operative radiation; five were active smokers and six were hypertensive. Complications included visibility in the upper pole (9.5%), seroma (1.6%), dehiscence, infection and necrosis (3.2% for each). Implant loss occurred in 3.2% of the cases. The patients were highly satisfied, reporting scores above 50 for each section of the Breast-Q questionnaire. With an acceptable complication rate, the use of the equine APM can be considered safe with satisfactory aesthetic results. Although the retrospective nature of this study limits its clinical impact, the use of Equity can be considered a viable alternative to thicker and expensive ADMs.

Histological analysis of elastic cartilages treated with alkaline solution

ABSTRACT The elastic cartilage is composed by chondroblasts and chondrocytes, extracellular matrix and surrounded by perichondrium. It has a low regeneration capacity and is a challenge in surgical repair. One of obstacles in engineering a structurally sound and long-lasting tissue is selecting the most appropriate scaffold material. One of the techniques for obtaining biomaterials from animal tissues is the decellularization that decreases antigenicity. In this work, alkaline solution was used in bovine ear elastic cartilages to evaluate the decellularization and the architecture of the extracellular matrix. The cartilages were treated in alkaline solution (pH13) for 72 hours and lyophilized to be compared with untreated cartilages by histological analysis (hematoxylin-eosin, Masson's trichrome and Verhoeff slides). Areas of interest for cell counting and elastic fiber quantification were delineated, and the distribution of collagen and elastic fibers and the presence of non-fibrous proteins were observed. The results demonstrated that the alkaline solution caused 90% decellularization in the middle and 13% in the peripheral region, and maintenance of the histological characteristics of the collagen and elastic fibers and non-fibrous protein removal. It was concluded that the alkaline solution was efficient in the decellularization and removal of non-fibrous proteins from the elastic cartilages of the bovine ear.

Multiparametric Optical Bioimaging Reveals the Fate of Epoxy Crosslinked Biomeshes in the Mouse Subcutaneous Implantation Model

Biomeshes based on decellularized bovine pericardium (DBP) are widely used in reconstructive surgery due to their wide availability and the attractive biomechanical properties. However, their efficacy in clinical applications is often affected by the uncontrolled immunogenicity and proteolytic degradation. To address this issue, we present here in vivo multiparametric imaging analysis of epoxy crosslinked DBPs to reveal their fate after implantation. We first analyzed the structure of the crosslinked DBP using scanning electron microscopy and evaluated proteolytic stability and cytotoxicity. Next, using combination of fluorescence and hypoxia imaging, X-ray computed microtomography and histology techniques we studied the fate of DBPs after subcutaneous implantation in animals. Our approach revealed high resistance to biodegradation, gradual remodeling of a surrounding tissue forming the connective tissue capsule and calcification of crosslinked DBPs. These changes were concomitant to the development of hypoxia in the samples within 3 weeks after implantation and subsequent induction of angiogenesis and vascularization. Collectively, presented approach provides new insights on the transplantation of the epoxy crosslinked biomeshes, the risks associated with its applications in soft-tissue reconstruction and can be transferred to studies of other types of implants.

Effect of axial prestretch and adipose tissue on the inflation-extension behavior of the human abdominal aorta

Our study aims to show that perivascular adipose tissue may significantly change the mechanical state of the abdominal aorta. To this end, uniaxial tensile tests with perivascular fat tissue were carried out. In the subsequent regression analysis, stress-strain data were fitted by the polynomial strain energy density. A constitutive model of adipose tissue was used in the analytical simulation of the inflation-extension behavior of the human abdominal aorta. The computational model was based on the theory of the bi-layered thick-walled tube. In addition to the effect of perivascular tissue, the effect of axial prestretch was also studied. It was found that the presence of perivascular tissue reduces the distensibility of the aorta. Axial prestretch applied to the aorta embedded in adipose tissue had an effect opposite to that of adipose tissue. Axially prestrained aorta exhibited higher distensiblity than non-prestrained aorta. It was also shown that the perivascular envelope bears some portion of the pressure loading and thus reduces the mechanical stresses inside the wall of aorta. A similar effect was found for axial prestretch.

Bovine Pericardial Graft for Second-Trimester Cesarean Scar Dehiscence

BACKGROUND

Cesarean scar dehiscence is rare in pregnancy. When it occurs late in pregnancy, management typically involves delivery of the fetus with concurrent uterine repair. However, consensus regarding management earlier in gestation is lacking.

CASE

A 30-year-old African American woman, gravida 5 para 2113, presented with cesarean scar dehiscence confirmed by magnetic resonance imaging at 20 weeks of gestation. She desired pregnancy continuation and underwent repair of the dehiscence at 23 weeks of gestation using bovine pericardial graft. She subsequently underwent cesarean delivery at 35 weeks of a healthy neonate after going into preterm labor.

CONCLUSION

Bovine pericardial graft is a viable option for repair of cesarean scar dehiscence in the second trimester.

Biomaterials for topical and transdermal drug delivery in reconstructive transplantation

Lifelong systemic immunosuppression remains the biggest challenge in vascularized composite allotransplantation (VCA) due to the adverse effects it causes. Since VCA is a life-enhancing procedure as compared with solid organ transplant which is life-saving; one needs to weigh the benefits and risks carefully. Thus, there is a huge unmet clinical need to design biomaterial-based vehicles that can deliver drugs more efficiently, topically and locally to eliminate adverse effects of systemic immune suppression. This review discusses several biomaterial-based systems that have been carefully designed, conceived and attempted to make VCA a more patient compliant approach. Variety of promising preclinical studies has shown the feasibility of the approaches, and clinical trials are required to bridge the gap. Several challenges for the future and new approaches have been discussed.

Biological acellular pericardial mesh regulated tissue integration and remodeling in a rat model of breast prosthetic implantation

The use of biological meshes has proven beneficial in surgical restriction and periprosthetic capsular contracture following breast prosthetic-reconstruction. Three different types (smooth, texturized, and polyurethane) of silicone round mini prostheses were implanted under rat skin with or without two different bovine acellular pericardial biological meshes (APMs, BioRipar, and Tutomesh). One hundred eighty-six female rats were divided into 12 groups, sacrificed after 3, 6, and 24 weeks and tissue samples investigated by histology and immunohistochemistry. Implantation of both APMs, with or without prostheses, reduced capsular α-SMA expression and CD3⁺ inflammatory cell infiltration, increasing capillary density and cell proliferation, with some differences. In particular, Tutomesh was associated with higher peri-APM CD3⁺ inflammation, prosthetic capsular dermal α-SMA expression and less CD31⁺ vessels and cell proliferation compared with BioRipar. None differences were observed in tissue integration and remodeling following the APM + prostheses implantation; the different prostheses did not influence tissue remodeling. The aim of our study was to investigate if/how the use of different APMs, with peculiar intrinsic characteristics, may influence tissue integration. The structure of APMs critically influenced tissue remodeling after implantation. Further studies are needed to develop new APMs able to optimize tissue integration and neoangiogenesis minimizing periprosthetic inflammation and fibrosis.

Processing of collagen based biomaterials and the resulting materials properties

Collagen, the most abundant extracellular matrix protein in animal kingdom belongs to a family of fibrous proteins, which transfer load in tissues and which provide a highly biocompatible environment for cells. This high biocompatibility makes collagen a perfect biomaterial for implantable medical products and scaffolds for in vitro testing systems. To manufacture collagen based solutions, porous sponges, membranes and threads for surgical and dental purposes or cell culture matrices, collagen rich tissues as skin and tendon of mammals are intensively processed by physical and chemical means. Other tissues such as pericardium and intestine are more gently decellularized while maintaining their complex collagenous architectures. Tissue processing technologies are organized as a series of steps, which are combined in different ways to manufacture structurally versatile materials with varying properties in strength, stability against temperature and enzymatic degradation and cellular response. Complex structures are achieved by combined technologies. Different drying techniques are performed with sterilisation steps and the preparation of porous structures simultaneously. Chemical crosslinking is combined with casting steps as spinning, moulding or additive manufacturing techniques. Important progress is expected by using collagen based bio-inks, which can be formed into 3D structures and combined with live cells. This review will give an overview of the technological principles of processing collagen rich tissues down to collagen hydrolysates and the methods to rebuild differently shaped products. The effects of the processing steps on the final materials properties are discussed especially with regard to the thermal and the physical properties and the susceptibility to enzymatic degradation. These properties are key features for biological and clinical application, handling and metabolization.

PRGF-Modified Collagen Membranes for Guided Bone Regeneration: Spectroscopic, Microscopic and Nano-Mechanical Investigations

The aim of our study was to evaluate the properties of different commercially available resorbable collagen membranes for guided bone regeneration, upon addition of plasma rich in growth factors (PRGF). The structural and morphological details, mechanical properties, and enzymatic degradation were investigated in a new approach, providing clinicians with new data in order to help them in a successful comparison and better selection of membranes with respect to their placement and working condition. Particular characteristics such as porosity, fiber density, and surface topography may influence the mechanical behavior and performances of the membranes, as revealed by SEM/AFM and nanoindentation measurements. The mechanical properties and enzymatic degradation of the membranes were analyzed in a comparative manner, before and after PRGF-modification. The changes in Young modulus values are correlated with the ultrastructural properties of each membrane type. The enzymatic (trypsin) degradation test also emphasized that PRGF-modified membranes exhibit a slower degradation compared to the native ones.