Xenogeneic Extracellular Matrix Research Articles

The effect of the αGal epitope in the response to ECM in a nonhuman primate model (141.26)

Abstract The Galα1,3Galβ1,4GlcNAc-R (Gal) Epitope is a major factor in the hyperacute rejection of pig organs transplants in primates. Biologic scaffold materials used for tissue reconstruction and composed of xenogeneic extracellular matrix (ECM) may contain the Gal epitope. However, the effect this epitope has upon the host response is controversial. The present study investigated the effect of the Gal epitope upon the host response to a porcine-derived ECM in an African Green monkey (Cholrocaebus aethiops) abdominal wall resection model. Histologic methods, serology, complement-dependent cytotoxicity (CDC) and gene expression profiling were used to evaluate the host response to allogeneic and both wild-type and Gal-deficient xenogeneic scaffold materials. Although expression of the Gal epitope induced an increase in serum anti-Gal antibodies in recipients, no other differences were noted in the host response between test articles. All ECM scaffolds were well tolerated and showed constructive remodeling during the test period. Recipients of all test articles showed no histologic or humoral evidence of sensitization when a second scaffold was implanted 45 days after the original surgery. The findings of the present study show that the Gal epitope within porcine-derived ECM scaffold material causes a serum antibody response, but no adverse effect upon tissue remodeling.

Immune Response to Xenogeneic Matrix Grafts Used in Pediatric Surgery

Lyoplant is an acellular, bovine derived extracellular matrix (ECM) that has been used for tissue remodelling and repair in numerous xenotransplantations. The aim of our study was to evaluate the inflammatory response and tensile strength after xenogeneic matrix (Lyoplant) implantation compared to the more widely used synthetic polypropylene matrix. Full-thickness abdominal wall defects were created in 15 Wistar WU rats and reconstructed with either a Lyoplant matrix (B. Braun Aesculap, Tuttlingen, Germany) or a Prolene matrix (a polypropylene matrix [PPP]; Prolene, Ethicon, Norderstedt, Germany). Animals in both the treatment and the control groups were checked daily for local and systemic complications. Bodyweight was recorded and the possible development of a hernia was monitored. After 6 weeks the abdomen was reopened and adhesions to the intestine were determined. Histopathology and immunohistochemistry were performed to evaluate the immunological reaction to the xenograft. Compared to the untreated animals, all rats had a physiological growth and bodyweight curve: No wound infection was observed during the experiment. An abdominal hernia developed at the implant site only in one rat treated with a PPP matrix. All other animals had an excellent clinical recovery and good cosmetic results. PPP animals showed a pronounced inflammatory response indicated by an increased number of fibroblasts. The Lyoplant matrix implantation induced an infiltration of CD4 and CD68 positive cells. In addition, active neovascularization was found, indicating a remodelling process. The inflammatory response in Lyoplant treated animals was significantly milder than in PPP implanted rats. Interestingly, some CD8 positive cells were detected in the Lyoplant group. A xenogeneic extracellular matrix, such as Lyoplant, may induce an immune response which is predominantly TH2-like and comparable with a remodelling reaction rather than rejection.

A Biodegradable, Acellular Xenogeneic Scaffold for Regeneration of the Vocal Fold Lamina Propria

A novel method for preparing an acellular xenogeneic extracellular matrix scaffold for tissue engineering was developed. Bovine vocal fold lamina propria specimens were treated with high-concentration sodium chloride, nucleic acid digestion, and ethanol dehydration for decellularization and removal of immunogenic foreign epitopes. Human vocal fold fibroblasts from primary culture were seeded onto the acellular scaffolds and cultured for 21 days. The decellularized and the recellularized scaffolds were examined by light microscopy, fluorescent microscopy, and scanning electron microscopy. Collagen synthesis and release by fibroblasts were quantified by the Sircol assay, whereas the synthesis and release of hyaluronic acid, decorin, and fibronectin were assessed by enzyme-linked immunosorbent assays. Viscoelastic shear properties of the scaffolds were quantified by a simple-shear rheometer at frequencies of up to 250 Hz. Preliminary results showed that a biodegradable, acellular extracellular matrix scaffold with an intact basement membrane and 3-dimensional structure of the matrix proteins was engineered. Vocal fold fibroblasts readily attached to and infiltrated the scaffold with high viability and active protein synthesis, demonstrating the biocompatibility. The elastic shear modulus and dynamic viscosity of the acellular scaffold and the fibroblast-repopulated scaffold were comparable to those of the human vocal fold cover. These findings support the potential of the scaffold as a xenograft for vocal fold reconstruction and regeneration.

Extracellular matrix for myocardial repair.

To evaluate the remodeling characteristics of an extracellular matrix (ECM) scaffold when used as a template for myocardial repair. Xenogeneic ECM has been shown to be an effective scaffold for the repair and reconstitution of several tissues, including lower urinary tract structures, dura mater, the esophagus, musculotendinous tissues, and blood vessels. These ECM scaffolds are completely degraded in vivo and induce a host cellular response that supports. Constructive remodeling rather than scar tissue formation. Full-thickness circular defects measuring approximately 2.5 cm in diameter were created in the right ventricular anterior walls of 6 adult Yucatán pigs and 4 adult mongrel dogs. The defects were repaired with an ECM sheet 80 m thick that was derived from either the porcine small intestinal submucosa or the porcine urinary bladder matrix. The animals lived for periods of 6 to 24 weeks before sacrifice. There was a complete replacement of the acellular scaffolds by a mixture of tissue types, including well-vascularized fibrous connective tissue, cartilage, adipose connective tissue, and myocardial tissue. The remodeled scaffold tissue showed spontaneous contractility and peak contractile force equivalent to 70% of the contractile force of the adjacent native myocardium. We conclude that porcine ECM scaffolds alter the typical scar tissue healing response in myocardial tissue and instead support vascularization and the local development of multiple tissue types, including contractile myocardium.

Xenogeneic extracellular matrix as a scaffold for tissue reconstruction

Xenogeneic extracellular matrix as a scaffold for tissue reconstruction

Xenogeneic extracellular matrix as a scaffold for tissue reconstruction

Bioscaffolds derived from xenogeneic extracellular matrix (ECM) have been used in numerous tissue engineering applications. The safety and efficacy of such scaffolds when used for the repair and reconstruction of numerous body tissues including musculoskeletal, cardiovascular, urogenital and integumentary structures has been shown in both preclinical animal studies and in human clinical studies. More than 200 000 human patients have been implanted with xenogeneic ECM scaffolds. These ECM scaffolds are typically prepared from porcine organs such as small intestine or urinary bladder, which are subjected to decellularization and terminal sterilization without significant loss of the biologic effects of the ECM. The composition of these bioscaffolds includes the structural and functional proteins that are part of native mammalian extracellular matrix. The three-dimensional organization of these molecules distinguishes ECM scaffolds from synthetic scaffold materials and is associated with constructive tissue remodeling instead of scar tissue. The biologic response to these xenogeneic bioscaffolds, including the immune response, is discussed herein.

Biaxial strength of multilaminated extracellular matrix scaffolds

Xenogeneic extracellular matrix (ECM) can be harvested and configured to function as a bioscaffold for tissue and organ reconstruction. The mechanical properties of the ECM vary depending upon the tissue from which it is harvested. Likewise, the manufacturing steps required to develop ECMs into medical grade devices will affect the surface morphology and the mechanical properties of the bioscaffold; important properties for constructive tissue remodeling. The present study compared the ball-burst strength of five different ECM scaffolds before and after treatment with peracetic acid (PAA): porcine small intestinal submucosa (SIS), porcine urinary bladder submucosa (UBS), porcine urinary bladder matrix (UBM), a composite of UBS+UBM, and canine stomach submucosa (SS). This study also compared the mechanical properties of 2- and 4-layer ECM scaffolds. Results showed 2-layer SS devices had the highest ball-burst value of all 2-layer ECM devices. Moreover, all 4-layer ECM devices had similar ball-burst strength except for 4-layer UBM devices which was the weakest. PAA-treatment decreased the ball-burst strength of SS and increased the ball-burst strength of UBS 2-layer devices. This study showed the material properties of the ECM scaffolds could be engineered to mimic those of native soft tissues (i.e. vascular, musculotendinous, etc) by varying the number of layers and modifying the disinfection/sterilization treatments used for manufacturing.

Extracellular matrix as a scaffold for laryngeal reconstruction.

Porcine-derived xenogeneic extracellular matrix (ECM) has been successfully used as a scaffold for tissue repair and reconstruction in numerous preclinical animal studies and human applications. These scaffolds are completely and rapidly degraded and replaced by host-derived tissues that frequently mimic the original tissue composition and architecture. The purpose of the present study was to examine the morphology of ECM scaffolds after their use for laryngeal reconstruction. Thirty adult female dogs were subjected to a partial hemilaryngectomy. The right thyroid cartilage and vocal fold were replaced with ECM scaffold, and the dogs were painlessly sacrificed from 1 week to 12 months after surgery. Histologic examination of the reconstructed tissue showed the presence of a simple squamous epithelial lining, organized glandular structures within the submucosa, reconstructed thyroid cartilage, and bundles of skeletal muscle by 3 months after surgery. We conclude that ECM scaffolds are promising templates for constructive remodeling of laryngeal tissue.

Use of Small Intestinal Submucosa for Corporal Body Grafting in Cases of Severe Penile Curvature

Use of Small Intestinal Submucosa for Corporal Body Grafting in Cases of Severe Penile Curvature

The Th2-Restricted Immune Response to Xenogeneic Small Intestinal Submucosa Does Not Influence Systemic Protective Immunity to Viral and Bacterial Pathogens

Implantation of mice with xenogeneic extracellular matrix (ECM) not only results in tissue remodeling but also elicits a strong Th2 immune response. It is possible that the Th2 cytokines induced by ECM act systemically and result in immune suppression to unrelated antigens. In this case, the recipient would be predisposed to immune dysfunction and have increased susceptibility to various pathogens. The purpose of this study was to determine if ECM implantation does, in fact, influence the immune response to other antigens. Four models were examined to determine the effects of ECM implantation on systemic immunity. In the first model, mice were subcutaneously implanted with porcine small intestinal submucosa (SIS) and immunized with a T-dependent subunit vaccine against influenza virus. The antibody response and protection against lethal infection were then measured. The second model consisted of similar experiments performed using a T-independent polysaccharide vaccine against S. pneumoniae. In the third model, mice were implanted and the cell-mediated response to dinitrofluorobenzene (DNFB) challenge was determined. The fourth model involved examining the influence of SIS implantation on rejection of xenogeneic skin grafts. We found that antibody levels of mice vaccinated against influenza virus or S. pneumoniae were not affected by SIS implantation and these mice did not exhibit increased or decreased susceptibility to either infectious agent. Similarly, mice implanted with ECM showed no cell-mediated immune dysfunction upon challenge with DNFB or xenogeneic skin grafts. The results of this study demonstrate that the Th2-restricted response induced by xenogeneic ECM implantation does not cause generalized immune suppression. Therefore, SIS implantation does not increase susceptibility to viral or bacterial pathogenic agents.

Xenogeneic extracellular matrix grafts elicit a TH2-restricted immune response.

Porcine small intestinal submucosa (SIS) is an acellular, naturally derived extracellular matrix (ECM) that has been used for tissue remodeling and repair in numerous xenotransplantations. Although a vigorous immune response to xenogeneic extracellular matrix biomaterials is expected, to date there has been evidence for only normal tissue regeneration without any accompanying rejection. The purpose of this study was to determine the reason for a lack of rejection. Mice were implanted s.c. with xenogeneic tissue, syngeneic tissue, or SIS, and the graft site analyzed histologically for rejection or acceptance. Additionally, graft site cytokine levels were determined by reverse transcriptase polymerase chain reaction and SIS-specific serum antibody isotype levels were determined by ELISA. Xenogeneically implanted mice showed an acute inflammatory response followed by chronic inflammation and ultimately graft necrosis, consistent with rejection. Syngeneically or SIS implanted mice, however, showed an acute inflammatory response that diminished such that the graft ultimately became indistinguishable from native tissue, observations that are consistent with graft acceptance. Graft site cytokine analysis showed an increase in interleukin-4 and an absence of interferon-gamma. In addition, mice implanted with SIS produced a SIS-specific antibody response that was restricted to the IgG1 isotype. Reimplantation of SIS into mice led to a secondary anti-SIS antibody response that was still restricted to IgG1. Similar results were observed with porcine submucosa derived from urinary bladder. To determine if the observed immune responses were T cell dependent, T cell KO mice were implanted with SIS. These mice expressed neither interleukin-4 at the implant site nor anti-SIS-specific serum antibodies but they did accept the SIS graft. Porcine extracellular matrix elicits an immune response that is predominately Th2-like, consistent with a remodeling reaction rather than rejection.

Resorbable bioscaffold for esophageal repair in a dog model

Purpose: Porcine-derived, xenogeneic extracellular matrix (ECM) derived from either the small intestinal submucosa (SIS) or urinary bladder submucosa (UBS) was used as a tissue scaffold for esophageal repair in a dog model. Methods: Patch defects measuring approximately 5 cm in length and encompassing 40% to 50% of the circumference of the esophagus or complete circumferential segmental defects measuring 5 cm in length were created by surgical resection in healthy adult female dogs. The defects were repaired with ECM scaffolds derived from either SIS or UBS. The animals were kept alive for periods ranging from 4 days to 15 months. Results: The xenogeneic scaffolds used for repair of the patch defects were resorbed completely within 30 to 60 days and showed replacement by skeletal muscle, which was oriented appropriately and contiguous with adjacent normal esophageal skeletal muscle, organized collagenous connective tissue, and a complete and intact squamous epithelium. No signs of clinical esophageal dysfunction were seen in any of the animals with the patch defect repair. The xenogeneic scaffolds configured into tubes for repair of the segmental defects all showed stricture within 45 days of surgery. Conclusion: These ECMs show promise as a treatment option for esophageal repair, but stricture remains problematic for complete tube grafts. J Pediatr Surg 35:1097-1103. Copyright © 2000 by W.B. Saunders Company.

Induction of hematopoietic microenvironment by the extracellular matrix from long-term bone marrow cultures

Extracellular matrix (ECM) plays an important role in the regulation of hematopoiesis. The ECM obtained from murine long-term bone marrow cultures (LTBMCs) induces hematopoietic foci formation within 3 months after implantation under the murine renal capsule. The foci consist of approximately 3 x 10(6) hematopoietic cells and function for at least 11 months. The induced stroma contains transplantable precursors capable of transferring a hematopoietic microenvironment to secondary recipients, and is insensitive to the stroma-stimulating factor produced in recipient mice after irradiation. The ECM induces hematopoietic foci formation in chimeras irradiated by a dose which is lethal for most of the stromal precursors. These facts point to the differences observed between bone marrow stromal precursors and mesenchymal cells induced under the renal capsule. The foci contain bone, but its appearance is limited to early stages of foci growth, and depends on the dose of implanted ECM. Bone is not formed when the xenogeneic ECM from nonhematopoietic tissue is used as an inducer. In this case, the foci develop slowly and are observed only to the tenth month after implantation. The data obtained demonstrate a novel function of the ECM in the induction of a hematopoietic microenvironment.