Xenogeneic Biomaterials Research Articles

Chronic graft-specific cell-mediated immune response toward candidate xenogeneic biomaterial.

Despite rabbits becoming an increasingly popular animal model, a flow cytometry panel that combines T cell markers (CD3, CD4, CD8, CD25, FOXP3) with a method for monitoring proliferation is lacking in this species. It has been shown that the rabbit model can be used to identify xenoantigens within bovine pericardium (BP), a common biological heart valve replacement material; however, these methods rely on monitoring the humoral immune response. The development of a rabbit T cell proliferation assay has utility in monitoring graft-specific cell-mediated immune responses toward bovine pericardium. Isolation and culture conditions were optimized to avoid cell death, red blood cell contamination, and non-specific proliferation. Effect of cell culture and stimulation on distribution and intensity of T cell markers was analyzed and compared between cells isolated from naïve and BP-immunized rabbits. Submaximal levels (0.25μg/mL) of concavalin A were used to stimulate proliferation toward BP extract, with resultant proliferation compared between naïve and BP-immunized rabbits. Density stratification followed by ammonium potassium chloride (ACK) lysis yielded the greatest number of viable peripheral blood mononuclear cells with the least amount of erythrocyte contamination. Flat-bottomed plates were necessary to reduce non-specific proliferation in culture. T cells responded appropriately to maximal mitogenic stimulation (5μg/mL concavalin A). Interestingly, immunization increased the intensity of FOXP3 in T regulatory cells compared to cells from naïve animals. With addition of submaximal levels of concavalin A, T cells from immunized rabbits proliferated in response to BP protein extract, while cells from naïve rabbits did not. In immunized rabbits, not only did more CD4+ T cells proliferate in response to BP re-stimulation, but the intensity of CD25 was increased indicating cell activation. This research provides a functional cell-mediated screening assay for assessment of BP-based biomaterials in rabbits, overcoming the limitations of previous humoral immune system-based assessments of biomaterial antigenicity in this important experimental animal species.

Biotechnological potential of by-products of the Brazilian animal protein industry in the generation of xenogeneic biomaterials for bone regeneration

Biotechnological potential of by-products of the Brazilian animal protein industry in the generation of xenogeneic biomaterials for bone regeneration

Comparative study of guided bone regeneration with synthetic and xenogenic biomaterials in mandibular defects of rats

Comparative study of guided bone regeneration with synthetic and xenogenic biomaterials in mandibular defects of rats

A review of decellurization methods caused by an urgent need for quality control of cell-free extracellular matrix' scaffolds and their role in regenerative medicine.

The natural extracellular matrix (ECM),thanks to its specific properties (e.g., collagenous lattice, a reservoir of growth factors, ECM-cell anchoring areas, an optimal pH and CO2 ),ensures an optimal microenvironment for homeostatic and regenerative cell development. In the context of regenerative medicine, ECM is a lair for residual and infiltrative cells. The aim of the clinical usage of cell-free ECM scaffolds is the enhancement of tissue regeneration with possible minimization of an adverse host reaction on allogeneic or xenogeneic biomaterial. Thus, the objective of decellularization is to obtain acellular grafts characterized by optimal biological properties, such as a lack of remaining cellular elements (e.g., cell membrane phospholipids and proteins, nucleic acids, mitochondria), lack of immunogenicity, lack of calcification promotion and lack of cytotoxicity (e.g., in unrinsed detergents). Furthermore, cell-free ECM scaffolds should present the optimal mechanical and structural properties that may ensure the biocompatibility of the graft. The maintenance of the ultrastructure composition of the ECM is one of the most important goals of decellularization. All physical, chemical, and biological methods proposed (used separately or in combination to extract cells from tissues/organs) are not 100% effective in cell removal and always cause a disruption of the ECM texture, as well as a probable loss of important structure components. Although cell-free ECM scaffolds are generally classified as medical devices, there are no widely accepted or legally defined criteria for quality control/evaluation methods of obtained matrices. Such criteria must be provided. Some of them have been proposed in this manuscript. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 106B: 909-923, 2018.

In vitro comparative assessment of decellularized bovine pericardial patches and commercial bioprosthetic heart valves

Notwithstanding their wide exploitation, biological prosthetic heart valves are characterized by limited durability (10–15 years). The treatment of biological tissues with chemical crosslinking agents such as glutaraldehyde accounts for the enhanced risk of structural deterioration associated with the early failure of bioprosthetic valves. To overcome the shortcomings of the currently available solutions, adoption of decellularized biological tissues of animal origin has emerged as a promising approach. The present study aims to assess in vitro cardiovascular scaffolds composed of bovine pericardium decellularized with the novel TRITDOC (TRIton-X100 and TauroDeOxyCholic acid) procedure. The effects of the treatment have been assessed by means of histological, biomolecular, cellular, biochemical and biomechanical analyses. The TRITDOC procedure grants the complete decellularization of bovine pericardial scaffolds while preserving the extracellular matrix architecture and the biomechanical properties. With a dedicated ELISA test, the TRITDOC procedure has been proven to ensure the complete removal of the alphaGal antigen, responsible for hyperacute rejection and for long-term deterioration of xenogenic biomaterials. Static seeding of the acellular pericardial patches with human adipose-derived stem cells resulted in an evenly repopulated scaffold without signs of calcification. The in vitro cyto-/immuno-compatibility response of the TRITDOC-bovine pericardium was compared with glutaraldehyde-treated xenogenic pericardium collected from two bioprosthetic devices currently used in clinical practice: PERIMOUNT MAGNA and TRIFECTATM. TRITDOC-bovine pericardium exhibited lower complement activation, lower cytotoxicity and a lower tendency to secrete pro-inflammatory cytokines compared to the tested commercial bioprostheses. Therefore, TRITDOC-decellularized pericardium could be considered as possible candidate material for the production of prosthetic heart valves.

In vivo xenogeneic scaffold fate is determined by residual antigenicity and extracellular matrix preservation

The immunological potential of animal-derived tissues and organs is the critical hurdle to increasing their clinical implementation. Glutaraldehyde-fixation cross-links proteins in xenogeneic tissues (e.g., bovine pericardium) to delay immune rejection, but also compromises the regenerative potential of the resultant biomaterial. Unfixed xenogeneic biomaterials in which xenoantigenicity has been ameliorated and native extracellular matrix (ECM) architecture has been maintained have the potential to overcome limitations of current clinically utilized glutaraldehyde-fixed biomaterials. The objective of this work was to determine how residual antigenicity and ECM architecture preservation modulate recipient immune and regenerative responses towards unfixed bovine pericardium (BP) ECM scaffolds. Disruption of ECM architecture during scaffold generation, with either SDS-decellularization or glutaraldehyde-fixation, stimulated recipient foreign body response and resultant fibrotic encapsulation following leporine subpannicular implantation. Conversely, BP scaffolds subjected to stepwise removal of hydrophilic and lipophilic antigens using amidosulfobetaine-14 (ASB-14) maintained native ECM architecture and thereby avoided fibrotic encapsulation. Removal of hydrophilic and lipophilic antigens significantly decreased local and systemic graft-specific, adaptive immune responses and subsequent calcification of BP scaffolds compared to scaffolds undergoing hydrophile removal only. Critically, removal of antigenic components and preservation of ECM architecture with ASB-14 promoted full-thickness recipient non-immune cellular repopulation of the BP scaffold. Further, unlike clinically utilized fixed BP, ASB-14-treated scaffolds fostered rapid intimal and medial vessel wall regeneration in a porcine carotid patch angioplasty model. This work highlights the importance of residual antigenicity and ECM architecture preservation in modulating recipient immune and regenerative responses towards xenogeneic biomaterial generation.

Postextraction Socket Seal Surgery with an Epithelized Connective Tissue Graft Using a Subpapillar Tunneling Procedure.

Ridge preservation in the esthetic area is still a challenging procedure. The aim of the present case series was to introduce a technique for postextraction socket seal surgery using an epithelized connective tissue graft and socket filling with a xenogeneic biomaterial. Using a tunneling approach, the buccal gingiva and interdental papillae are undermined and augmented with the soft tissue graft. This method was applied and evaluated in 16 sites in 13 patients with need for extraction of at least one maxillary anterior tooth. Five months postoperative, the mean reduction of the horizontal width of the alveolar ridge was 0.5 mm, while the height of the mesial and distal papillae were reduced by 0.2 mm and 0.4 mm, respectively. The buccogingival margin of the alveolar ridge showed a vertical gain of 0.5 mm. Therefore, the presented technique seems appropriate for preservation of the alveolar ridge in esthetically relevant areas.

Simultaneous Sinus Augmentation with Implant Placement: Histomorphometric Comparison of Two Different Grafting Materials. A Multicenter Double-Blind Prospective Randomized Controlled Clinical Trial

Sinus elevation via the lateral approach for implant rehabilitation of atrophic posterior maxillae is considered a safe and predictable therapy. Several xenogeneic biomaterials of different biologic origin have been used as valid and predictable alternatives to autogenous bone. This multicenter randomized controlled double-blind prospective clinical trial aimed to compare histomorphometrically two xenogeneic grafting materials used for sinus elevation with simultaneous implant placement. Seven private practices in Italy were involved. Patients presenting at least one site with a residual bone crest height between 2 and 4 mm were treated. Control sites were grafted with 100% deproteinated particulated bovine bone (DPBB), while test sites were grafted with prehydrated corticocancellous porcine bone (PCPB). Root-form implants were placed simultaneously. Insertion torque and clinical stability were assessed and recorded. At 6 months, a biopsy specimen was harvested from each site, and histomorphometric analyses were performed. Thirty-seven patients received 42 sinus elevations (24 test and 18 control). Eighty-two implants with adequate primary stability were placed. Fifty-five implants were placed in residual bone crests greater than 2 mm but less than 4 mm (average 2.7 mm) and achieved an average insertion torque of 22.8 ± 11.3 N/cm. Nineteen implants were placed in ridges greater than 3 mm but less than 5 mm, and eight were placed in ridges with more than 5 mm remaining. After 6 months, three implants had failed to integrate, leading to a survival rate of 96.34%. Forty-two specimens were analyzed histomorphometrically. No significant differences in total bone volume (PCPB 37.43%, DPBB 37.52%) or residual grafting material (PCPB 13.55%, DPBB 16.44%) were detected. In this study, PCPB compared well with DPBB as a grafting material for lateral sinus elevation.

Histological Evaluation on Biocompatibility of Porcine Liver Derived ECM Matrix

As promising transplantable biomedical strategies for liver supports, decellularized porcine matrix have been explored. For safe medical application of xenogenic biomaterials, studies would be required to focus on the biocompatibility and host cellular responses to implanted biologic materials. This study was assessed the biocompatibility of extracellular matrix (ECM)-rich matrix from porcine liver as transplantable biomaterials. Porcine liver tissues were decellularized with 0.1% Sodium dodeocyl sulfate solution. To compare host remodeling responses of liver matrix, native and decellularized liver samples are implanted into subcutaneous of pig for 10weeks. After 1, 2, 4, and 10 weeks of surgery, the implanted samples were harvested and examined by Hematoxylin and Eosin staining. The degree of acute inflammation, chronic inflammation, eosinophilic infiltration, vascularity, and stromal reaction was graded on a scale of 0(+) to 4(++++). Decellularized matrix implants represented only minimal chronic inflammatory responses. No acute inflammatory responses, eosinophilc infiltrations, and vascularities were represented in the decellularized matrix implant groups. Mild to moderate degree of fibroblasts infiltration was seen around and within the both native liver and decellularized matrix implant groups. Complete degradation of all implanted tissues was occurred within10 weeks. Porcine liver biologic scaffolds would be beneficial for diverse studies related to liver regeneration. Although additional in-depth studies would be required to analysis mechanisms of host immune responses to biologic scaffolds, our data provide useful information of vivo remodeling properties of porcine liver biologic matrix. This work was supported by a grant from the Next-Generation BioGreen 21 program (No.P J008030,J008032), Rural Development Administration, Republic of Korea.

Decellularized Extracellular Matrix Derived from Porcine Adipose Tissue as a Xenogeneic Biomaterial for Tissue Engineering

Cells in tissues are surrounded by the extracellular matrix (ECM), a gel-like material of proteins and polysaccharides that are synthesized and secreted by cells. Here we propose that the ECM can be isolated from porcine adipose tissue and holds great promise as a xenogeneic biomaterial for tissue engineering and regenerative medicine. Porcine adipose tissue is easily obtained in large quantities from commonly discarded food waste. Decellularization protocols have been developed for extracting an intact ECM while effectively eliminating xenogeneic epitopes and minimally disrupting the ECM composition. Porcine adipose tissue was defatted by homogenization and centrifugation. It was then decellularized via chemical (1.5 M sodium chloride and 0.5% sodium dodecyl sulfate) and enzymatic treatments (DNase and RNase) with temperature control. After decellularization, immunogenic components such as nucleic acids and α-Gal were significantly reduced. However, abundant ECM components, such as collagen (332.9±12.1 μg/mg ECM dry weight), sulfated glycosaminoglycan (GAG, 85±0.7 μg/mg ECM dry weight), and elastin (152.6±4.5 μg/mg ECM dry weight), were well preserved in the decellularized material. The biochemical and mechanical features of a decellularized ECM supported the adhesion and growth of human cells in vitro. Moreover, the decellularized ECM exhibited biocompatibility, long-term stability, and bioinductivity in vivo. The overall results suggest that the decellularized ECM derived from porcine adipose tissue could be useful as an alternative biomaterial for xenograft tissue engineering.

Biomechanical and structural changes following the decellularization of bovine pericardial tissues for use as a tissue engineering scaffold

To achieve natural scaffolds for tissue engineering applications we decellularized bovine pericardial (BP) tissues according to two different protocols: a novel treatment based on Triton(®) X-100 (12 h, 4 °C) (BP1) and a trypsin/EDTA treatment (37 °C, 48 h) (BP2). Results were compared with commercially available acellular xenogeneic biomaterials, Veritas(®) and Collamed(®). Biomechanical characteristics, high (E(h)) and low (E(l)) modulus of elasticity, of the fresh untreated tissue varied with the anatomical direction (apex to base (T) to transverse (L)) (mean ± SDEV): (41.63 ± 14.65-48.12 ± 10.19 MPa and 0.27 ± 0.05-0.30 ± 0.12 MPa respectively). BP1 had no mechanical effect (44.65 ± 19.73-52.67 ± 7.59 MPa and 0.37 ± 0.14-0.37 ± 0.11 MPa, respectively) but BP2 resulted in significant decrease in E(h) and E(l) (20.96 ± 8.17-36.82 ± 3.23 MPa and 0.20 ± 0.06-0.23 ± 0.06 MPa). Hysteresis ratio (h) varied (19-26 % of the loading energy) independently of anatomical direction. Glycosaminoglycans content was unaffected by BP1, while 22 % of chondroitin/dermatan sulphate and 60 % of hyaluronan were removed after BP2 treatment. Endothelial cell adhesion was achieved after 24 h and 3 days cell culture.

The effect of collagenated space filling materials in sinus bone augmentation: a study in rabbits

The inclusion of biomaterial particles used for alveolar bone regeneration in a carrier or in binding agents such as collagen gel or fibers is of interest as a means to help with surgical handling. However, the possible influence of collagen on bone tissue response to biomaterials is poorly studied. The objective of the present study was to investigate, in a sub-sinus bone augmentation model in rabbits, the effect of collagen at different stages of the osteogenesis process. Histologic, histomorphometric and volumetric analyses were performed. Rabbits underwent a double sinus lift procedure using bovine hydroxyapatite (BHA), collagenated bovine hydroxyapatite (BHAColl), and prehydrated and collagenated porcine hydroxyapatite (PHAColl). Animals were sacrificed at 1week, 5weeks or 6months. Samples were subjected to X-ray micro-tomography and histology. Qualitative analysis was performed on the non-decalcified sections and quantitative histomorphometric analyses were conducted using scanning electron microscopy (SEM). Volume variations of bone augmentations were calculated at different time points. The three biomaterials allowed an optimal bone formation and were able to equally withstand sinusal reexpansion. A comparable percentage of new bone, as well as 3D volume stability, was found between the groups at each time point. However, the PHAColl resorption rate was significantly higher than the rates in other groups (P=0.0003), with only 3.6% of the particles remaining at 6months. At 1week, both collagenated groups displayed the presence of inflammatory cells although BHA did not show any sign of inflammation. At 5weeks and 6months, the inflammatory process had disappeared completely in the BHAColl groups, whereas some inflammatory-like cells could still be observed around the remaining particles of PHAColl. Within the limitations of this study in rabbits, the findings showed the presence of inflammatory-like cells at the early stage of bone regeneration when collagenated xenogenic biomaterials were used compared to xenogenic granules alone. Nevertheless, similar bone formation occurred and comparable 3D volumes were found at 6months in the different groups.

Solid-state NMR and IR characterization of commercial xenogeneic biomaterials used as bone substitutes

Three commercial xenogeneic biomaterials (Gen-Os, Apatos Spongiosa and Apatos Cortical; all from Tecnoss Dental, Torino, Italy) originated from porcine bone were characterized by various analytical methods, such as powder X-ray diffraction (XRD), thermogravimetry (TGA), high-resolution solid-state nuclear magnetic resonance (ssNMR) and infrared spectroscopy (FT-IR). The studies were focused on structural properties and chemical compositions of the samples. It was found that the main constituents of the analyzed biomaterials were nanocrystalline apatite mineral, organic collagenous matrix and water. For comparison, synthetic carbonated hydroxyapatite and natural collagen type I from bovine tendon were used. Differences in various physicochemical parameters such as crystal size, specific surface area, concentration of structural hydroxyl groups, contents of CO 3 2− and HPO 4 2− ions and their location were discussed. It was shown that various techniques of ssNMR and elaborate analysis of the FT-IR spectra, applied together, provide valuable information on xenogeneic biomaterials.

The role of protein solubilization in antigen removal from xenogeneic tissue for heart valve tissue engineering

Decellularization techniques have been developed in an attempt to reduce the antigenicity of xenogeneic biomaterials, a critical barrier in their use as tissue engineering scaffolds. However, numerous studies have demonstrated inadequate removal and subsequent persistence of antigens in the biomaterial following decellularization, resulting in an immune response upon implantation. Thus, methods to enhance antigen removal (AR) are critical for the use of xenogeneic biomaterials in tissue engineering and regenerative medicine. In the present study, AR methods incorporating protein solubilization principles were investigated for their ability to reduce antigenicity of bovine pericardium (BP) for heart valve tissue engineering. Bovine pericardium following AR (BP-AR) was assessed for residual antigenicity, tensile properties, and extracellular matrix composition. Increasing protein solubility during AR significantly decreased the residual antigenicity of BP-AR—by an additional 80% compared to hypotonic solution or 60% compared to 0.1% (w/v) SDS decellularization methods. Moreover, solubilizing agents have a dominant effect on reducing the level of residual antigenicity of BP-AR beyond that achieved by AR additives alone. Tested AR methods did not compromise the tensile properties of BP-AR compared to native BP. Furthermore, residual cell nuclei did not correlate to residual antigenicity, demonstrating that residual nuclei counts may not be an appropriate indicator of successful AR. In conclusion, AR strategies promoting protein solubilization significantly reduced residual antigens compared to decellularization methods without compromising biomaterial functional properties. This study demonstrates the importance of solubilizing protein antigens for their removal in the generation of xenogeneic scaffolds.

Comparison of postoperation bone defects healing of alveolar processes of maxilla and mandible with the use of Bio-Gen and Bio-Oss

Bone defects of mandible and maxilla alveolar processes have often iatrogenic origins, because they appear as a consequence of performed operations. Bone atrophy may be stopped by filling bone defects with augmentative biomaterial directly after an oral surgery procedure. To achieve this aim augmentative biomaterials are used. Many years of experimental studies confirmed xenogenic biomaterials as the most ef fective. The aim of this study was clinical assessment of bone lesions healing with the use of Bio-Gen and Bio-Oss materials. A comparison of radiological imaging of healed defects was performed, as well as histological analysis of biopsies obtained from the defect sites. The structure analysis of both materials was performed with the use of electron microscopy. Chemical ingredients of analyzed biomaterials were assessed with the use of X-ray microanalysis. Postoperation follow-up in all groups was done. Histological and radiological analysis of regeneration course were performed. Radiological analysis was performed with the use of Digora 2,1 system, which allows to asses optical density of images. Histopathologic regenerates were analyzed morfometrically. The results of this study confirmed effectiveness of Bio-Gen and Bio-Oss materials in regeneration of bone defects. Six month long follow-up period confirmed a significant increase of the optical density of regenerates augmented with Bio-Gen and Bio-Oss comparing to lesions healed without biomaterial augmentation.

Physicochemical characterization of two deproteinized bovine xenografts

Calcium phosphate salts, or more specifically hydroxyapatite, are products of great interest in the fields of medical and dental science due to their biocompatibility and osteoconduction property. Deproteinized xenografts are primarily constituted of natural apatites, sintered or not. Variations in the industrial process may affect physicochemical properties and, therefore, the biological outcome. The purpose of this work was to characterize the physical and chemical properties of deproteinized xenogenic biomaterials, Bio-Oss (Geistlich Biomaterials, Wolhuser, Switzerland) and Gen-Ox (Baumer S.A., Brazil), widely used as bone grafts. Scanning electron microscopy, infrared region spectroscopy, X-ray diffraction, thermogravimetry and degradation analysis were conducted. The results show that both materials presented porous granules, composed of crystalline hydroxyapatite without apparent presence of other phases. Bio-Oss presented greater dissolution in Tris-HCl than Gen-Ox in the degradation test, possibly due to the low crystallinity and the presence of organic residues. In conclusion, both commercial materials are hydroxyapatite compounds, Bio-Oss being less crystalline than Gen-Ox and, therefore, more prone to degradation.

Proteomic analysis of the extent and distribution of immunogenic proteins in xenogeneic bioscaffolds

Objective Decellularized xenogeneic bioscaffolds offer the possibility of serving as a platform for tissue engineering. However, the full extent and distribution of xenoantigens in these materials have not been explored. We used a proteomic approach to identify immunogenic proteins in a candidate xenogeneic biomaterial. Methods - Cytoplasmic and membrane proteins were extracted from bovine pericardium (BP) using differential solubility and precipitation techniques. Extracted proteins were separated by either 1d or 2d gel electrophoresis. Western blots were performed using serum from rabbits collected before and after immunization with homogenized BP. Blots were probed with anti-rabbit IgG light chain specific secondary antibody (Jackson ImmunoResearch). Target proteins were digested with trypsin and assessed using MALDI-TOF/TOF mass spectroscopy. Protein identifications were made using MASCOT software to compare MS data to various databases (eg NCBInr, SWISS-PROT). Results - IgG specific anti-BP antibodies were found in both pre and post immunization serum. The distribution of these antibodies was mainly towards cytoplasmic proteins in the pre-immunization serum. Rapid and persistent development of anti-BP antibodies was found post-immunization, directed mainly at membrane proteins. Conclusion Rabbit serum contains pre-existing IgG antibodies directed towards several cytoplasmic proteins in BP. Following exposure to BP, rabbits exhibit a rapid and persistent development of IgG anti-BP antibodies, which are mainly directed towards membrane proteins.

Evaluation of a Xenogeneic Acellular Collagen Matrix as a Small-Diameter Vascular Graft in Dogs-Preliminary Observations

Autogenous veins are the materials of choice for arterial reconstruction. In the absence of autogenous material, prosthetic materials are used. However, vascular prostheses of less than 0.4 cm in diameter have low long-term patency. This study was designed to determine if cells would infiltrate an engineered xenogeneic biomaterial used as a smalldiameter arterial graft in dogs and, if so, to determine the phenotype of the infiltrating cells. Nine acellular xenogeneic grafts (0.4 cm in diameter, 5 cm long), composed of porcine collagen derived from the submucosa of the small intestine and type I bovine collagen, were implanted as end-to-end interposition grafts in femoral arteries of five male mongrel dogs (total of nine grafts). All dogs received daily aspirin (325 mg). Patency of implanted grafts was monitored weekly by Duplex ultrasonography. After 9 weeks, or earlier in case of blood flow reduction by at least 75%, grafts were explanted and prepared for light or electron microscopy to evaluate cellularization. Eight of nine grafts remained patent up to 9 weeks. At explant, diameters were 0.31 - 0.02 cm at the midgraft, and 0.14 - 0.01 and 0.19 - 0.01 cm at the proximal and distal anastomoses. At explant, cells of mesenchymal origin (endothelial cells, smooth muscle cells, myofibroblasts) were embedded in the extracellular matrix of the graft scaffold. Minimal evidence of cellular inflammatory reaction and no aneurysmal dilatation or thrombus formation was detected. Variable degrees of hyperplasia were present at proximal and distal anastomoses. This preliminary study demonstrates that a collagen-based xenogeneic biomaterial provides a scaffold for cellularization when used for arterial reconstruction in dogs.

Shape and orientation of osteoblast-like cells (Saos-2) are influenced by collagen fibers in xenogenic bone biomaterial.

The surface topography of a substratum has been shown to influence the growth and morphology of cells in culture. In this study, human osteoblast-like cells (Saos-2) were cultured on two types of xenogenic biomaterials obtained from bovine bone. Both biomaterials were similar in architectural organization and surface topography, but they differed in matrix components. The first one was characterized by preservation of the mineralized collagen matrix, and the second by complete deproteinization which only preserved the mineral phase. Cells cultured at the surface of both biomaterials were observed using scanning electron microscopy. The beta 1-integrin subunit, known to bind cell and collagen, is the major integrin of the osteoblast. It was localized using immunogold in transmission electron microscopy. At the surface of the collagen-containing matrix, cells exhibited an elongated shape and oriented axis parallel to the underlying collagen bundles. The beta 1-integrin subunit was localized at the outer surface of cells, in close association with collagen and at the contact points between cells and biomaterials. In contrast, at the surface of the single mineral matrix, cells were round shaped with random disposition. Gold particles were found around the cells with no specific relation to the biomaterial. These results strongly suggest that the chemical nature of the surface of a bone biomaterial directly influences adhesion process, shape, and spatial organization of cultured osteoblastic cells.