Collagen Coatings Research Articles

Collagen-Mimetic Proteins with Tunable Integrin Binding Sites for Vascular Graft Coatings.

Achieving graft endothelialization following implantation continues to be a challenge in the development of "off-the-shelf," small-caliber, arterial prostheses. Coating grafts with biomolecules to support the retention, migration, and differentiation of adherent endothelial precursor cells (EPCs) is a promising approach toward improving graft endothelialization. Designer Collagen Scl2-2 with 1 integrin binding site per strand (DC2-1X) is a Streptococcus pyogenes-derived, collagen-like protein that has previously been evaluated as a graft coating due to its ability to resist platelet aggregation and to promote attachment and migration of "late outgrowth" EPCs (EOCs). However, these prior assessments were performed in the absence of physiological shear. In addition, although DC2-1X coatings supported increased migration rates relative to native collagen coatings, EOC attachment and spreading remained inferior to collagen controls at all DC2-1X concentrations assayed. Thus, the objectives of the present work were the following: (1) to improve EOC attachment on DC2 coatings by modulating the number and spacing of DC2 integrin binding sites (IBS) and (2) to evaluate the retention, migration, and differentiation of adherent EOCs under physiological shear stress. Using single point mutations, three novel DC2 variants were generated containing either two IBS (DC2-2X) or three IBS (DC2-3X1 and DC2-3X2) per strand. After initial evaluation of the potential of each DC2 variant to support increased EOC attachment relative to DC2-1X, DC2-2X and DC2-3X1 coatings were further assessed under physiological shear for their capacity to promote EOC retention, migration, and differentiation relative to DC2-1X and collagen controls. An increase in the number of IBS from 1 to 3 significantly improved EOC retention on DC2 coatings while also supporting increased average migration rates. Moreover, EOCs on DC2-3X1 coatings showed increased gene-level expression of intermediate endothelial cell differentiation markers relative to collagen. Overall, the current results suggest that DC2-3X1 warrants further investigation as a vascular graft coating.

Magnetically Assisted Electrodeposition of Aligned Collagen Coatings.

Well-aligned collagen nanofibers are crucial in engineering bioinspired regenerative strategies, such as bone, muscle and cornea. However, keeping the natural bioactive of collagen and controlling its orientation in a coating still remain a challenge. Here we present a novel magnetically assisted electrochemical technique to deposit type-I collagen nanofibers with high alignment onto titanium. The magnetic assistance involved mainly the incorporation of iron oxide nanoparticles (IOPs) and the application of an external magnetic field during the electrochemical deposition. The combination of IOPs with the collagen nanofibrils in electrolyte endowed the nanofibrils with magnetism, which forced the collagen nanofibrils to be straightened and assembled into aligned nanofibers under magnetic field during electrodeposition. The influence of the applied magnetic field on orientational order of the collagen nanofibers in the coatings extended to drying stage. The aligned collagen coatings demonstrated to favorably guide the bone marrow mesenchymal stem cells (BMSCs) grow in the form of elongated morphology, which promoted the cellular osteogenic differentiation dramatically. The present magnetically assisted electrodeposition could emerge as an attractive approach to fabrication of aligned nanofibers on substrates for subsequent uses such as bone tissue engineering.

Magnetically actuated mechanical stimuli on Fe3O4/mineralized collagen coatings to enhance osteogenic differentiation of the MC3T3-E1 cells

Mechanical stimuli at the bone-implant interface are considered to activate the mechanotransduction pathway of the cell to improve the initial osseointegration establishment and to guarantee clinical success of the implant. However, control of the mechanical stimuli at the bone–implant interface still remains a challenge. In this study, we have designed a strategy of a magnetically responsive coating on which the mechanical stimuli is controlled because of coating deformation under static magnetic field (SMF). The iron oxide nanoparticle/mineralized collagen (IOP-MC) coatings were electrochemically codeposited on titanium substrates in different quantities of IOPs and distributions; the resulting coatings were verified to possess swelling behavior with flexibility same as that of hydrogel. The relative quantity of IOP to collagen and the IOP distribution in the coatings were demonstrated to play a critical role in mediating cell behavior. The cells present on the outer layer of the distributed IOP-MC (O-IOP-MC) coating with a mass ratio of 0.67 revealed the most distinct osteogenic differentiation activity being promoted, which could be attributed to the maximized mechanical stimuli with exposure to SMF. Furthermore, the enhanced osteogenic differentiation of the stimulated MC3T3-E1 cells originated from magnetically actuated mechanotransduction signaling pathway, embodying the upregulated expression of osteogenic-related and mechanotransduction-related genes. This work therefore provides a promising strategy for implementing mechanical stimuli to activate mechanotransduction on the bone–implant interface and thus to promote osseointegration. Statement of SignificanceThe magnetically actuated coating is designed to produce mechanical stimuli to cells for promoting osteogenic differentiation based on the coating deformation. Iron oxide nanoparticles (IOPs) were incorporated into the mineralized collagen coatings (MC) forming the composite coatings (IOP-MC) with spatially distributed IOPs, and the IOP-MC coatings with outer distributed IOPs (O-IOPs-MC) shows the maximized mechanical stimuli to cells with enhanced osteogenic differentiation under static magnetic field. The upregulated expression of the associated genes reveals that the enabled mechanotransduction signaling pathway is responsible for the promoted cellular osteogenic differentiation. This work therefore provides a promising strategy for implementing mechanical stimuli to activate mechanotransduction on the bone–implant interface to promote osseointegration.

Sulfation degree not origin of chondroitin sulfate derivatives modulates keratinocyte response

Chondroitin sulfate (CS) sulfation-dependently binds transforming growth factor-β1 (TGF-β1) and chronic wounds often accompany with epidermal hyperproliferation due to downregulated TGF‐β signaling. However, the impact of CS on keratinocytes is unknown. Especially biotechnological-chemical strategies are promising to replace animal-derived CS. Thus, this study aims to evaluate the effects of CS derivatives on the interaction with vascular endothelial growth factor-A (VEGF-A) and on keratinocyte response.Over-sulfated CS (sCS3) interacts stronger with VEGF-A than CS. Furthermore, collagen coatings with CS variants are prepared by in vitro fibrillogenesis. Stability analyses demonstrate that collagen is firmly integrated, while the fibril diameters decrease with increasing sulfation degree. CS variants sulfation-dependently decelerate keratinocyte (HaCaT) migration and proliferation in a scratch assay. HaCaT cultured on sCS3-containing coatings produced increased amounts of solute active TGF-β1 which could be translated into biomaterials able to decrease epidermal hyperproliferation in chronic wounds. Overall, semi-synthetic and natural CS yield to comparable responses.

Selecting the correct cellular model for assessing of the biological response of collagen-based biomaterials.

Integrins play a vital role in cellular responses to environmental cues during early-stage cell-substrate interaction. We describe physiologically relevant cell anchorage to collagen substrates that present different affinity cell-recognition motifs, to provide experimental tools to assist in understanding integrin binding. Using different cell types and recombinant integrin α1-I-domains, we found that cellular response was highly dependent on collagen type, origin and EDC-crosslinking status, as well as on the integrin class and species of origin. This comprehensive study establishes selectivity amongst the four collagen-binding integrins and species-specific properties that together may influence choice of cell type and receptor in different experimental settings. This work offers key guidance in selecting of the correct cellular model for the biological testing of collagen-based biomaterials.

Abstract: Dipyridamole Releasing 3D Printed Bioactive Ceramic Scaffolds with Osseoconductive Geometries Promote Craniofacial Bone Regeneration

INTRODUCTION: The standard of care for critical-sized bony defects is autologous bone tissue transfer. However, its limitations (e.g., morbidity, secondary procedures, cost) have driven progress in alternatives such as tissue engineering-based treatments. We explored the bone regenerative capacity of customized, 3D printed bioactive ceramic (3DBC) scaffolds with dipyridamole (DIPY), an adenosine A2A receptor (A2AR) indirect agonist known to enhance bone formation, at the ramus of the rabbit mandible. METHODS: Critical-sized bony defects (10mm height, 10mm length, full thickness) were created at the inferior aspect of the right mandibular rami of rabbits, adjacent to the angular process (n=15). Each defect was replaced by a custom-to-defect, 3DBC printed porous scaffold composed of β-tricalcium phosphate. Scaffolds were either uncoated (control), collagen-coated (COLL), or collagen coated and immersed in 100μM dipyridamole (DIPY). At t=8 weeks, animals were euthanized and the rami retrieved. Bone growth was assessed exclusively within scaffold pores, and evaluated by microCT/advanced reconstruction computer software. MicroCT quantification was calculated in segments as a function of distance from proximal to distal scaffold insertion. Bone morphology was assessed by histology. One-way ANOVA analysis was performed to compare group means, and 95% confidence intervals (CI) were included. RESULTS: Qualitative analysis did not show an inflammatory response. On 3D analysis, the control and COLL groups (12.3 ± 8.3% and 6.9 ± 8.3% bone occupancy of free space, respectively) had less bone growth, while the most bone growth was in the DIPY group (26.9 ± 10.7%), a statistically significant difference (p<0.03 DIPY vs. control and p<0.01 DIPY vs. COLL). Evaluation of scaffold presence resulted in a significantly higher presence of material for the COLL group relative to the DIPY group (p<0.015), whereas the control group presented intermediate values (non-significant relative to both COLL and DIPY). A general linear mixed model was performed for bone growth as a function of distance from the most proximal (deepest) aspect scaffold insertion site to the most superficial (distal at the mandibular border) aspect, for which DIPY-treated scaffolds demonstrated the most bone growth at the thinnest region of ramus bone at the proximal defect. Highly cellular and vascularized intramembranous-like bone healing was observed in all groups. CONCLUSION: COL-DIPY significantly increased the 3DBC scaffold’s ability to regenerate bone. Irrespective of treatment group, all scaffolds demonstrated bone regeneration with predominant focal growth at bone-scaffold interfaces.

Hypoxia impairs agonist-induced integrin \u03b1IIb\u03b23 activation and platelet aggregation

Under ischemic conditions, tissues are exposed to hypoxia. Although human physiology, to a certain extent, can adapt to hypoxic conditions, the impact of low oxygen levels on platelet function is unresolved. Therefore, we explored how reduction of atmospheric oxygen levels to 1% might affect agonist-induced aggregation and static adhesion of isolated human platelets. We uncovered that isolated, washed human platelets exposed to hypoxic conditions show reduced thrombin receptor-activating peptide-6 (TRAP-6) and convulxin-induced aggregation. Of note, this hypoxia-triggered effect was not observed in platelet-rich plasma. Independent of the agonist used (TRAP-6, ADP), activation of the platelet fibrinogen receptor integrin αIIbβ3 (GPIIbIIIa, CD41/CD61) was strongly reduced at 1% and 8% oxygen. The difference in agonist-induced integrin αIIbβ3 activation was apparent within 5 minutes of stimulation. Following hypoxia, re-oxygenation resulted in the recovery of integrin αIIbβ3 activation. Importantly, platelet secretion was not impaired by hypoxia. Static adhesion experiments revealed decreased platelet deposition to fibrinogen coatings, but not to collagen or vitronectin coatings, indicating that specifically the function of the integrin subunit αIIb is impaired by exposure of platelets to reduced oxygen levels. Our results reveal an unexpected effect of oxygen deprivation on platelet aggregation mediated by the fibrinogen receptor integrin αIIbβ3.

Controlled Release of Naringin in Metal-Organic Framework-Loaded Mineralized Collagen Coating to Simultaneously Enhance Osseointegration and Antibacterial Activity.

Two important goals in orthopedic implant research are to promote osseointegration and prevent infection. However, much previous effort has been focused on the design of coatings to either enhance osseointegration while ignoring antibacterial activity or vice versa, to prevent infection while ignoring bone integration. Here, we designed a multifunctional mineralized collagen coating on titanium with the aid of metal-organic framework (MOF) nanocrystals to control the release of naringin, a Chinese herbal medicine that could promote osseointegration and prevent bacterial infection. The attachment, proliferation, osteogenic differentiation, and mineralization of mesenchymal stem cells on the coating were significantly enhanced. Meanwhile, the antibacterial abilities against Staphylococcus aureus were also promoted. Furthermore, release kinetics analysis indicated that the synergistic effect of a primary burst release stage and secondary slow release stage played a critical role in the performance and could be controlled by the relative concentrations of MOF and naringin. This work thus provides a novel strategy to engineer multifunctional orthopedic coatings that can enhance osseointegration and simultaneously inhibit microbial cell growth.

PERITONEAL ADHESIONS TYPE I, III AND TOTAL COLLAGEN ON POLYPROPYLENE AND COATED POLYPROPYLENE MESHES: EXPERIMENTAL STUDY IN RATS

ABSTRACTBackground: Hernia correction is a routinely performed treatment in surgical practice. The improvement of the operative technique and available materials certainly has been a great benefit to the quality of surgical results. The insertion of prostheses for hernia correction is well-founded in the literature, and has become the standard of treatment when this type of disease is discussed. Aim: To evaluate two available prostheses: the polypropylene and polypropylene coated ones in an experimental model. Methods: Seven prostheses of each kind were inserted into Wistar rats (Ratus norvegicus albinus) in the anterior abdominal wall of the animal in direct contact with the viscera. After 90 days follow-up were analyzed the intra-abdominal adhesions, and also performed immunohistochemical evaluation and videomorphometry of the total, type I and type III collagen. Histological analysis was also performed with hematoxylin-eosin to evaluate cell types present in each mesh. Results: At 90 days the adhesions were not different among the groups (p=0.335). Total collagen likewise was not statistically different (p=0.810). Statistically there was more type III collagen in the coated polypropylene group (p=0.039) while type I was not different among the prostheses (p=0.050). The lymphocytes were statistically more present in the polypropylene group (p=0.041). Conclusion: The coated prosthesis was not different from the polypropylene one regarding the adhesion. Total and type I collagen were not different among the groups, while type III collagen was more present on the coated mesh. There was a greater number of lymphocytes on the polypropylene mesh.

Robust Generation of Quiescent Porcine Valvular Interstitial Cell Cultures.

BackgroundValvular interstitial cells (VICs) in the healthy aortic valve leaflet exhibit a quiescent phenotype, with <5% of VICs exhibiting an activated phenotype. Yet, in vitro culture of VICs on tissue culture polystyrene surfaces in standard growth medium results in rapid transformation to an activated phenotype in >90% of cells. The inability to preserve a healthy VIC phenotype during in vitro studies has hampered the elucidation of mechanisms involved in calcific aortic valve disease. This study describes the generation of quiescent populations of porcine VICs in 2‐dimensional in vitro culture and their utility in studying valve pathobiology.Methods and ResultsWithin 4 days of isolation from fresh porcine hearts, VICs cultured in standard growth conditions were predominantly myofibroblastic (activated VICs). This myofibroblastic phenotype was partially reversed within 4 days, and fully reversed within 9 days, following application of a combination of a fibroblast media formulation with culture on collagen coatings. Specifically, culture in this combination significantly reduced several markers of VIC activation, including proliferation, apoptosis, α‐smooth muscle actin expression, and matrix production, relative to standard growth conditions. Moreover, VICs raised in a fibroblast media formulation with culture on collagen coatings exhibited dramatically increased sensitivity to treatment with transforming growth factor β1, a known pathological stimulus, compared with VICs raised in either standard culture or medium with a fibroblast media formulation.ConclusionsThe approach using a fibroblast media formulation with culture on collagen coatings generates quiescent VICs that more accurately mimic a healthy VIC population and thus has the potential to transform the study of the mechanisms of VIC activation and dysfunction involved in the early stages of calcific aortic valve disease.

Three-Dimensional Coculture Model to Analyze the Cross Talk Between Endothelial and Smooth Muscle Cells.

The response of blood vessels to physiological and pathological stimuli partly depends on the cross talk between endothelial cells (EC) lining the luminal side and smooth muscle cells (SMC) building the inner part of the vascular wall. Thus, the in vitro analysis of the pathophysiology of blood vessels requires coculture systems of EC and SMC. We have developed and validated a modified three-dimensional sandwich coculture (3D SW-CC) of EC and SMC using open μ-Slides with a thin glass bottom allowing direct imaging. The culture dish comprises an intermediate plate to minimize the meniscus resulting in homogenous cell distribution. Human umbilical artery SMC were sandwiched between coatings of rat tail collagen I. Following SMC quiescence, human umbilical vein EC were seeded on top of SMC and cultivated until confluence. By day 7, EC had formed a confluent monolayer and continuous vascular endothelial (VE)-cadherin-positive cell/cell contacts. Below, spindle-shaped SMC had formed parallel bundles and showed increased calponin expression compared to day 1. EC and SMC were interspaced by a matrix consisting of laminin, collagen IV, and perlecan. Basal messenger RNA (mRNA) expression levels of E-selectin, angiopoietin-1, calponin, and intercellular adhesion molecule 1 (ICAM-1) of the 3D SW-CC was comparable to that of a freshly isolated mouse inferior vena cava. Addition of tumor necrosis factor alpha (TNF α) to the 3D SW-CC induced E-selectin and ICAM-1 mRNA and protein induction, comparable to the EC and SMC monolayers. In contrast, the addition of activated platelets induced a significantly delayed but more pronounced activation in the 3D SW-CC compared to EC and SMC monolayers. Thus, this 3D SW-CC permits analyzing the cross talk between EC and SMC that mediate cellular quiescence as well as the response to complex activation signals.

Extracellular matrix components and culture regimen selectively regulate cartilage formation by self-assembling human mesenchymal stem cells in vitro and in vivo.

BackgroundCartilage formation from self-assembling mesenchymal stem cells (MSCs) in vitro recapitulate important cellular events during mesenchymal condensation that precedes native cartilage development. The goal of this study was to investigate the effects of cartilaginous extracellular matrix (ECM) components and culture regimen on cartilage formation by self-assembling human MSCs in vitro and in vivo.MethodsHuman bone marrow-derived MSCs (hMSCs) were seeded and compacted in 6.5-mm-diameter transwell inserts with coated (type I, type II collagen) or uncoated (vehicle) membranes, at different densities (0.5 × 106, 1.0 × 106, 1.5 × 106 per insert). Pellets were formed by aggregating hMSCs (0.25 × 106) in round-bottomed wells. All tissues were cultured for up to 6 weeks for in vitro analyses. Discs (cultured for 6, 8 or 10 weeks) and pellets (cultured for 10 weeks) were implanted subcutaneously in immunocompromised mice to evaluate the cartilage stability in vivo.ResultsType I and type II collagen coatings enabled cartilage disc formation from self-assembling hMSCs. Without ECM coating, hMSCs formed dome-shaped tissues resembling the pellets. Type I collagen, expressed in the prechondrogenic mesenchyme, improved early chondrogenesis versus type II collagen. High seeding density improved cartilage tissue properties but resulted in a lower yield of disc formation. Discs and pellets exhibited compositional and organizational differences in vitro and in vivo. Prolonged chondrogenic induction of the discs in vitro expedited endochondral ossification in vivo.ConclusionsThe outcomes of cartilage tissues formed from self-assembling MSCs in vitro and in vivo can be modulated by the control of culture parameters. These insights could motivate new directions for engineering cartilage and bone via a cartilage template from self-assembling MSCs.

Influence of Halide Solutions on Collagen Networks: Measurements of Physical Properties by Atomic Force Microscopy.

The influence of aqueous halide solutions on collagen coatings was tested. The effects on resistance against indentation/penetration on adhesion forces were measured by atomic force microscopy (AFM) and the change of Young's modulus of the coating was derived. Comparative measurements over time were conducted with halide solutions of various concentrations. Physical properties of the mesh-like coating generally showed large variability. Starting with a compact set of physical properties, data disperse after minutes. A trend of increase in elasticity and permeability was found for all halide solutions. These changes were largest in NaI, displaying a logical trend with ion size. However a correlation with concentration was not measured. Adhesion properties were found to be independent of mechanical properties. The paper also presents practical experience for AFM measurements of soft tissue under liquids, particularly related to data evaluation. The weakening in physical strength found after exposure to halide solutions may be interpreted as widening of the network structure or change in the chemical properties in part of the collagen fibres (swelling). In order to design customized surface coatings at optimized conditions also for medical applications, halide solutions might be used as agents with little impact on the safety of patients.

Collagen and heparan sulfate coatings differentially alter cell proliferation and attachment in vitro and in vivo.

Tissue engineering is an innovative field of research applied to treat intestinal diseases. Engineered smooth muscle requires dense smooth muscle tissue and robust vascularization to support contraction. The purpose of this study was to use heparan sulfate (HS) and collagen coatings to increase the attachment of smooth muscle cells (SMCs) to scaffolds and improve their survival after implantation. SMCs grown on biologically coated scaffolds were evaluated for maturity and cell numbers after 2, 4 and 6 weeks in vitro and both 2 and 6 weeks in vivo. Implants were also assessed for vascularization. Collagen-coated scaffolds increased attachment, growth and maturity of SMCs in culture. HS-coated implants increased angiogenesis after 2 weeks, contributing to an increase in SMC survival and growth compared to HS-coated scaffolds grown in vitro. The angiogenic effects of HS may be useful for engineering intestinal smooth muscle.

Spatially-controlled distribution of HACC in mineralized collagen coatings for improving rhBMP-2 loading and release behavior

In this study, mineralized collagen (COL) coatings with controlled loading and release of bone morphogenetic protein (rhBMP-2) as well as enhanced osteogenic differentiation were successfully achieved via the spatially-control of hydroxypropyltrimethyl ammonium chloride chitosan (HACC) within the coatings. The distribution of HACC in the inner part (HACC-IN) or the outer part (HACC-OUT) of the coatings were adjusted by different potential values and negative/positive alternations during alternating potentials assisted electrochemical deposition (AP-ECD). It was found that rhBMP-2 loading capacity was remarkably enhanced with the increased incorporation of HACC due to their strong interaction, and the release behavior was also tuned by HACC location. In general, HACC-IN coatings showed a prominent improvement in cytocompatibility and osteogenic differentiation. The main reason is considered that the inner location of HACC can eliminate the negative effect of HACC to initial cellular adhesion and bring to a sustained rhBMP-2 release behavior due to kinetic modification. An optimized coating in this work could load as high as 4644ng/cm2 rhBMP-2 and release only 25% for 14 days, which consequently leads to a better osteogenic differentiation. This study has thus inspired another promising protocol for designing growth factor incorporated bioactive coatings for bone implants with improved osteointegration.

Electrochemical deposition of mineralized BSA/collagen coating

In this work, mineralized collagen coatings with different loading quantity of bovine serum albumin (BSA) were prepared via in situ electrochemical deposition on titanium substrate. The microstructure and BSA loading quantity of the coatings could be controlled by the electrochemical deposition parameters, such as deposition potential, BSA concentration and its adding sequence in the electrolyte. The BSA loading quantity in the coatings was obtained in the range of 0.0170–0.173mg/cm2, enhancing the cell adhesion and proliferation of the coatings with the simultaneous release. The distinct release behaviors of BSA were attributed to their gradient distribution with different mineralization degrees, which could be adjusted by the deposition process. These results suggest that in situ electrochemical deposition is a promising way to incorporate functional molecules into the mineralized collagen coatings and the mineralized BSA/collagen coatings are highly promising for improving the rhBMP-2 loading capability (1.8-fold).

Analysis of the biocompatibility of perfluoropolyether dimethacrylate network using an organotypic method

In this work, we have investigated the potential of perfluoropolyether (PFPE) polymers for use in biomaterial applications, especially in cell culture and tissue engineering. PFPE substrates were synthesized by the photocuring of liquid PFPE urethane dimethacrylate. These surfaces were then modified by ECM protein coatings and microstructuration, to promote cell adhesion and migration. The surface properties of PFPE and PDMS (used as a reference) samples were studied by static contact angle measurements and AFM imaging. Both polymer surfaces were hydrophobic, having sessile air–water contact angles superior to 100°. Collagen and fibronectin coatings were found to change the wettability of PFPE and PDMS samples. The biological testing of substrates was done using a liver organotypic culture to evaluate the migration and density of liver cells. The results over seven days of culture demonstrated that the migration and density of cells cultured under untreated PFPE were higher than the migration and density of cells cultured under PDMS. ECM protein coatings enhanced cell migration from liver explants cultured on PFPE or PDMS. Furthermore, these coatings were more efficient in the case of a PFPE sample. From a second series of tests, in which the PFPE was microstructured, it was found that microstructures promoted the formation of a 3D cell layer. These results indicate that PFPE polymers have a potential for use in the development of biomaterials for tissue engineering and cell culture.

Self-healing Characteristics of Collagen Coatings with Respect to Surface Abrasion.

A coating based on collagen with self-healing properties was developed for applications in mechanical components that are prone to abrasion due to contact with a counter surface. The inherent swelling behavior of collagen in water was exploited as the fundamental mechanism behind self-healing of a wear scar formed on the surface. The effects of freeze-drying process and water treatment of the collagen coatings on their mechanical and self-healing properties were analyzed. Water was also used as the medium to trigger the self-healing effect of the collagen coatings after the wear test. It was found that collagen coatings without freeze-drying did not demonstrate any self-healing effect whereas the coatings treated by freeze-drying process showed remarkable self-healing effect. Overall, collagen coatings that were freeze-dried and water treated showed the best friction and self-healing properties. Repeated self-healing ability of these coatings with respect to wear scar was also demonstrated. It was also confirmed that the self-healing property of the collagen coating was effective over a relatively wide range of temperature.

Mesenchymal Stem Cell Mediated Chondrogenesis on Chitosan-Calcium Phosphate Scaffolds: Effect of Collagen Coating

Mesenchymal Stem Cell Mediated Chondrogenesis on Chitosan-Calcium Phosphate Scaffolds: Effect of Collagen Coating

Assessment of collagen versus non collagen coated anterior vaginal mesh in pelvic reconstructive surgery: prospective study

ObjectiveTo evaluate the sonologic and clinical outcome of collagen coated (CC) versus non-collagen coated (NC) anterior vaginal mesh (AVM) for pelvic organ prolapse (POP) surgery. Study designThe study is a prospective observational study which included 122 patients who had symptomatic POP stage III and IV. AvaultaPlus™ (collagen coated, CC group) was compared to Perigee™ (non collagen coated, NC group). Introital ultrasound morphology, measure of neovascularization by color Doppler and clinical outcomes were assessed. Student t test was used for comparison of pre- and post-operation continuous data (p value of <0.05). ResultsA total of 110 (CC group=50, NC group=60) women completed the study. A woman in the CC group developed ureteral injury. Both groups had comparable morphologic and clinical outcomes however, the onset of changes in mesh thickness and neovascularization occurred earlier in the NC group (1 month) compared to the CC group (6 months to 1 year). ConclusionCC group was comparable to the NC group in terms of erosion rate, ultrasound and clinical assessment. Collagen coating may induce delayed inflammatory response however may also delay tissue integration.The onset of changes in mesh thickness and neovascularization may give us an insight toward utilization of collagen coated mesh for host-tissue integration.