Wall Defects In Rats Research Articles

Fabrication of a modified bacterial cellulose with different alkyl chains and its prevention of abdominal adhesion

Abdominal hernia mesh is a common product which is used for prevention of abdominal adhesion and repairing abdominal wall defect. Currently, designing and preparing a novel bio-mesh material with prevention of adhesion, promoting repair and good biocompatibility simultaneously remain a great bottleneck. In this study, a novel siloxane-modified bacterial cellulose (BC) was designed and fabricated by chemical vapor deposition silylation, then the effects of different alkyl chains length of siloxane on surface properties and cell behaviors were explored. The effect of preventing of abdominal adhesion and repairing abdominal wall defect in rats with the siloxane-modified BC was evaluated. As the grafted alkyl chains become longer, the surface of the siloxane-modified BC can be transformed from super hydrophilic to hydrophobic. In vivo results showed that BC-C16 had good long-term anti-adhesion effect, good tissue adaptability and histocompatibility, which is expected to be used as a new anti-adhesion hernia repair material in clinic.

Injectable Double Crosslinked Hydrogel-Polypropylene Composite Mesh for Repairing Full-Thickness Abdominal Wall Defects.

Abdominal wall defects are common clinical diseases, and mesh repair is the standard treatment method. The most commonly used polypropylene (PP) mesh in clinical practice has the advantages of good mechanical properties, stable performance, and effective tissue integration effect. However, direct contact between abdominal viscera and PP mesh can lead to severe abdominal adhesions. To prevent this, the development of a hydrogel-PP composite mesh with anti-adhesive properties may be an effective measure. Herein, biofunctional hydrogel loaded with rosmarinic acid is developed by modifying chitosan and Pluronic F127, which possesses suitable physical and chemical properties and commendable in vitro biocompatibility. In the repair of full-thickness abdominal wall defects in rats, hydrogels are injected onto the surface of PP mesh and applied to intraperitoneal repair. The results indicate that the use of hydrogel-PP composite mesh can alleviate abdominal adhesions resulting from traditional PP mesh implantation by decreasing local inflammatory response, reducing oxidative stress, and regulating the fibrinolytic system. Combined with the tissue integration ability of PP mesh, hydrogel-PP composite mesh has great potential for repairing full-thickness abdominal wall defects.

GelMA/tannic acid hydrogel decorated polypropylene mesh facilitating regeneration of abdominal wall defects.

Polypropylene (PP) mesh is a widely used prosthetic material in hernia repair due to its excellent mechanical properties and appropriate biocompatibility. However, its application is limited due to severe adhesion between the mesh and the abdominal viscera, leading to complications such as chronic pain, intestinal obstruction, and hernia recurrence. Currently, building anti-adhesive PP mesh remains a formidable challenge. In this work, a novel anti-adhesive PP mesh (PPM/GelMA/TA) was designed with a simple and efficient in situ gel of GelMA solution on the surface of PP mesh and further crosslinking of tannic acid (TA). It was demonstrated that PPM/GelMA/TA has good biocompatibility and excellent antioxidant property and effectively activates the polarization of macrophages toward the M2 phenotype in vitro. In addition, PPM/GelMA/TA could inhibit the growth of bacteria, which is of great significance for preventing postoperative infections. Furthermore, in the repair of full-thickness abdominal wall defects in rats, PPM/GelMA/TA reduced inflammation, promoted macrophage M2 polarization, and collagen deposition and angiogenesis so that does not cause any abdominal adhesion compared with PP mesh. As a result, our PPM/GelMA/TA shows an attractive prospect in the treatment of abdominal wall defect without adhesions.

Experimental reconstruction of an abdominal wall defect with electrospun polycaprolactone-ureidopyrimidinone mesh conserves compliance yet may have insufficient strength

PurposeElectrospun meshes mimic the extracellular matrix, which may improve their integration. We aimed to compare polycaprolactone (PCL) modified with ureidopyrimidinone (UPy) electrospun meshes with ultra-lightweight polypropylene (PP; Restorelle) reference textile meshes for in vivo compliance. We chose UPy-PCL because we have shown it does not compromise biomechanical properties of native tissue, and because it potentially can be bioactivated. MethodsWe performed ex vivo biomechanical cyclic loading in wet conditions and in vivo overlay of full-thickness abdominal wall defects in rats and rabbits. Animals were sacrificed at 7, 42 and 54 days (rats; n = 6/group) and 30 and 90 days (rabbits; n = 3/group). Outcomes were herniation, mesh degradation and mesh dimensions, explant compliance and histology. High failure rates prompted us to provide additional material strength by increasing fiber diameter and mesh thickness, which was further tested in rabbits as a biomechanically more challenging model. ResultsCompliance was tested in animals without herniation. In both species, UPy-PCL-explants were as compliant as native tissue. In rats, PP-explants were stiffer. Contraction was similar in UPy-PCL and PP-explants. However, UPy-PCL-meshes macroscopically degraded from 30 days onwards, coinciding with herniation in up to half of animals. Increased fiber and mesh thickness did not improve outcome. Degradation of UPy-PCL is associated with an abundance of foreign body giant cells until UPy-PCL disappears. ConclusionAbdominal wall reconstruction with electrospun UPy-PCL meshes failed in 50%. Degradation coincided with a transient vigorous foreign body reaction. Non-failing UPy-PCL-explants were as compliant as native tissue. Despite that, the high failure rate forces us to explore electrospun meshes based on other polymers.

Study of a new biodegradable hernia patch to repair abdominal wall defect in rats

A novel biodegradable chitin hernia patch was prepared by acetylation of chitosan fabric in our study. Physicochemical properties, cell compatibility and biodegradability of the chitin patch were quantified. Histopathological study of the functional experiment showed that this newly designed hernia patch promoted collagen deposition and neovascularization by significantly promoting the secretion of FGF1 and TGF-β1 in the early postoperative (P<0.01). Chitin patch caused less inflammation by inhibiting excessive expression of IL-6 and TNF-α when compared to the polypropylene mesh (P<0.01). Acceptable fibrosis was consistent with the results of immunohistochemistry studies. The density of FGF1 and TGF-β1 positive cells in the chitin patch group at 7 d was reduced to a lower level at 15 d (P<0.01). With regeneration of the defect abdominal wall, chitin patch degraded gradually, avoiding foreign body response and chronic complications. Our studies demonstrated that the newly designed chitin patch showed good promise for the hernia treatment.

Polypropylene mesh seeded with fibroblasts: A new approach for the repair of abdominal wall defects in rats.

The purpose of study was to develop bioengineered scaffolds by seeding primary mouse embryo fibroblast cells (p-MEF) on polypropylene mesh and to test its efficacy for the repair of abdominal wall defects in rats. The study was conducted on 18 clinically healthy adult Wistar rats of either sex. The animals were randomly divided into two equal groups having nine animals in each group. In both the groups a 20mm×20mm size full thickness muscle defect was created under xylazine and ketamine anesthesia in the mid-ventral abdominal wall. In group I the defect was repaired with polypropylene mesh alone and in group II it was repaired with p-MEF seeded polypropylene mesh. Matrices were implanted by synthetic absorbable suture material (polyglycolic acid) in continuous suture pattern. The efficacy of the bio-engineered matrices in the reconstruction of full thickness abdominal wall defects was evaluated on the basis of macro and histopathological observations. Macroscopic observations revealed that adhesions with skin and abdominal viscera were minimum in group II as compared to group I. Histopathological observations confirmed better fibroplasia and collagen fiber arrangement in group II. No recurrence of hernia was found in both the groups. Hernias are effectively repaired by implanting polypropylene mesh. However, this work demonstrates that in vitro seeding of mesh with fibroblasts resulted in earlier subsidization of pain, angiogenesis and deposition of collagen, increased thickness of matrices with lesser adhesions with underlying viscera. On the basis of the results p-MEF seeded mesh was better than non-seeded mesh for repair of abdominal wall defects in rats.

Perfusion-decellularized skeletal muscle as a three-dimensional scaffold with a vascular network template

There exists a great need for repair grafts with similar volume to human skeletal muscle that can promote the innate ability of muscle to regenerate following volumetric muscle loss. Perfusion decellularization is an attractive technique for extracellular matrix (ECM) scaffold from intact mammalian organ or tissue which has been successfully used in tissue reconstruction. The perfusion-decellularization of skeletal muscle has been poorly assessed and characterized, but the bioactivity and functional capacity of the obtained perfusion skeletal muscle ECM (pM-ECM) to remodel in vivo is unknown. In the present study, pM-ECM was prepared from porcine rectus abdominis (RA). Perfusion-decellularization of porcine RA effectively removed cellular and nuclear material while retaining the intricate three-dimensional microarchitecture and vasculature networks of the native RA, and many of the bioactive ECM components and mechanical properties. In vivo, partial-thickness abdominal wall defects in rats repaired with pM-ECM showed improved neovascularization, myogenesis and functional recellularization compared to porcine-derived small intestinal submucosa (SIS). These findings show the biologic potential of RA pM-ECM as a scaffold for supporting site appropriate, tissue reconstruction, and provide a better understanding of the importance maintaining the tissue-specific complex three-dimensional architecture of ECM during decellularization and regeneration.

Use of surgical mesh of different compositions in the correction of the abdominal wall defect in rats.

To analyze the performance of two surgical meshes of different compositions during the defect healing process of the abdominal wall of rats. thirty-three adult Wistar rats were anesthetized and subjected to removal of an area of 1.5 cm x 2 cm of the anterior abdominal wall, except for the skin; 17 animals had the defect corrected by edge-to-edge surgical suture of a mesh made of polypropylene + poliglecaprone (Group U--UltraproTM); 16 animals had the defect corrected with a surgical mesh made of polypropylene + polidioxanone + cellulose (Group P--ProceedTM). Each group was divided into two subgroups, according to the euthanasia moment (seven days or 28 days after the operation). Parameters analyzed were macroscopic (adherence), microscopic (quantification of mature and immature collagen) and tensiometric (maximum tension and maximum rupture strength). there was an increase in collagen type I in the ProceedTM group from seven to 28 days, p = 0.047. Also, there was an increase in the rupture tension on both groups when comparing the two periods. There was a lower rupture tension and tissue deformity with ProceedTM mesh in seven days, becoming equal at day 28. the meshes retain similarities in the final result and more studies with larger numbers of animals must be carried for better assessment.

Use of alloplastic meshes in abdominal wounds of rats with induced peritonitis

BackgroundThe use of alloplastic meshes has been historically contra-indicated in patients with infection.AimTo evaluate the use of polypropylene meshes in the treatment of abdominal wall defects in rats with peritonitis.MethodsTwenty Wistar female rats were divided into two groups: induction of peritonitis (test group) and without peritonitis (control group). An abdominal wall defect was created in all animals, and polypropylene mesh was applied. The evaluation of the tensile strength of the mesh was carried out using tensiometer and microscopic analysis of the healing area was done.ResultsMore adhesion of the mesh to the rat abdominal wall was observed in test group. The histopathological analyses showed prevalence of moderate to accentuated granulation tissue in both groups, without significant differences.ConclusionThe use of the mesh coverage on abdominal wall defects of rats with induced peritonitis did not show worse results than its use in healthy animals, nor was its integration to the resident tissue any worse.

Nonwoven polypropylene prosthesis in large abdominal wall defects in rats

To evaluate, in large abdominal wall defects surgically shaped in rats, if a synthetic polypropylene nonwoven prosthesis could be used as a therapeutic option to conventional polypropylene mesh. Twenty four (24) Wistar rats were enrolled into three groups. Group 1 (Simulation group) with an abdominal wall defect of 3 X 3 left untreated and Groups 2 and 3, respectively treated with a conventional polypropylene mesh and a polypropylene nonwoven (NWV) prosthesis to cover the breach. At the 45th postoperatively day, adhesion (area and strength) and vascularization of Groups 2 and 3 were evaluated. The histological preparations with Hematoxylin-Eosin, Tricromium of Masson, Pricrosirius red and polarization with birefringence, and also the structural analysis of the prostheses carried on by Thermogravimetry and Differential Scanning Calorimetry were also assessed. There were no significant differences between the Groups 2 and 3. In rats, the polypropylene nonwoven prosthesis showed to be safe and has to be considered as an alternative to conventional mesh manufactured by weaving in the treatment of great defects of the abdominal wall.

Comparative study between meshes of polyester with collagen and polytetrafluoroethylene in the repair of defects produced in abdominal wall of rats

To study the intraperitoneal use of polyester with collagen and polytetrafluoroethylene meshes in the correction of total ventral wall defects in rats. Thirty two rats were evaluated and divided randomly into four groups and underwent laparotomy and preparation of total defects of the abdominal wall. Next, the correction of the defect with the intraperitoneal placement of the chosen mesh was performed. The rats were submitted to euthanasia at 30 and 90 days after surgery. Were analyzed the macroscopic adhesions and microscopic aspects, and applied stress rupture test All animals showed intraperitoneal adhesions in varying degrees, with no statistical significance difference. There was no difference also between groups in the evaluation of stress rupture tests. On the microscopic aspect, the A30 group had less inflammatory reaction and less formation of granulomas and foreign body reaction that the B30 group, with significant difference. There was no difference in intraperitoneal adhesion and tensile rupture strength among groups. Group B30 presented granulomatous inflammatory reaction at the site of mesh attachment to the wall significantly higher than the A30.

Comparative study between polypropylene and polypropylene/poliglecaprone meshes used in the correction of abdominal wall defect in rats

To evaluate the healing process of a defect in the ventral abdominal wall of rats, comparing the polypropylene and polypropylene/poliglecaprone meshes on the 30(th) and 60(th) postoperative day. Thirty two Wistar rats were submitted to a ventral abdominal wall defect, with integrity of the parietal peritoneum. In the repair, were used polypropylene (group A) and polypropylene/poliglecaprone (group B) meshes. The groups were subdivided into four subgroups of eight animals euthanized on the 30(th) (A30 and B30) and 60(th) postoperative day (A60 and B60). Fragments of the abdominal wall of the animals were submitted to macroscopic, tensiometric and histological evaluations. The tensiometry on subgroup A30 showed a mean average break point of 0.78 MPa and in A60, 0.66 Mpa. In subgroup B30 it was 0.84 MPa and in B60, 1.27 Mpa. The score of the inflammatory process showed subacute phase on A30 and B30 sub-groups and chronic inflammatory process in subgroups A30 and 60B. The tensile strength was higher on the wall repaired by polypropylene/poliglecaprone mesh in the 60(th) post-operative day. Histology showed higher concentration of fibrosis on the surface of the polypropylene mesh with a tendency to encapsulation. In polypropylene/poliglecaprone subgroups the histology showed higher concentration of fibrosis on the surface of mesh filaments.

The biomechanical behavior and host response to porcine-derived small intestine submucosa, pericardium and dermal matrix acellular grafts in a rat abdominal defect model

Several porcine-derived acellular biologic grafts are increasingly used in abdominal wall reconstruction due to the limitations of synthetic meshes in many clinical situations. However, relatively little is known so far about their comparative mechanical characteristics and performance after defect repair. We therefore investigated three most commonly used porcine-derived acellular biomaterials, small intestine submucosa (P-SIS), pericardium (P-PC) and acellular dermal matrix (P-ADM) immediately after prepared, and their effectiveness, biomechanical and histological characteristics in repairing full-thickness abdominal defect in a rat model. P-PC had the best native performance in the burst strength, tensile strength and ball burst among the three porcine-derived scaffolds. P-SIS showed a significantly higher water vapor transmission in comparison with P-PC or P-ADM. Abdominal wall defects in rats were all satisfied repaired with P-SIS, P-PC or P-ADM. No laxity or fistula was observed in the repaired abdominal wall in the P-SIS group up to 8 weeks after surgery. However, there was a tendency for high postoperative abdominal eventration in the P-ADM and P-PC groups as compared with the P-SIS group. With regard to overall aspects of the postoperative laxity, intra-abdominal adhesion formation, tensile stress, stretchability, and degree of tissue ingrowth in terms of collagen deposition and neovascularization, P-SIS exhibits clear advantages over P-PC as well as P-ADM after large abdominal wall defect reconstruction.

Comparison of Two Porcine-Derived Materials for Repairing Abdominal Wall Defects in Rats

ObjectiveThe purpose of this study was to compare the mechanical properties, host responses and incorporation of porcine small intestine submucosa (PSIS) and porcine acellular dermal matrix (PADM) in a rat model of abdominal wall defect repair.Materials and MethodsPrior to implantation, PSIS and PADM were prepared and evaluated in terms of structure and mechanical properties. Full-thickness abdominal wall defects were created in 50 Sprague-Dawley rats, and were repaired using either PSIS or PADM. Rats were sacrificed 1, 2, 4, 8 and 12 weeks post-repair and examined for herniation, infection, adhesions, contraction, and changes in the thickness and strength of the tissues incorporated at the defect sites. Histopathology and immunohistochemistry were performed to analyze inflammatory responses, collagen deposition and vascularization.ResultsPADM showed more dense collagen deposition and stronger mechanical properties than PSIS prior to implantation (P<0.01). However, the mechanical properties observed after integration with the surrounding native tissues was similar for PADM and PSIS. Both PADM and PSIS showed significant contraction by week 12. However, PADM tissue induced less adhesion and increased in thickness more slowly, and showed less infiltration by foreign giant cells, polymorphonuclear cells, and mononuclear cells. Improved remodeling of host tissue was observed after PSIS implantation, which was apparent from the orientation of bands of fibrous connective tissue, intermixed with newly formed blood vessels by Week 12.ConclusionPSIS showed weaker mechanical properties prior to implantation. However, after implantation PSIS induced more pronounced host responses and showed better incorporation into host tissues than PADM.

Regeneration of full-thickness abdominal wall defects in rats using collagen scaffolds loaded with collagen-binding basic fibroblast growth factor

Biomaterials are increasingly used in the repair of tissue defects. The aim of the present study was to evaluate a new composite biomaterial for reconstruction of a 2 × 2.5 cm full-thickness abdominal wall defect. In this study, the collagen membrane was activated with the engineered human basic fibroblast growth factor (bFGF). To enhance the binding of bFGF to collagen membranes, a specific peptide of collagen-binding domain (CBD) was fused to the N-terminal of bFGF. After implantation, little adhesion was caused in collagen/CBD-bFGF, collagen/NAT-bFGF and collagen/PBS groups. Moreover, collagen/CBD-bFGF group could effectively promote the vascularization at 30 d after surgery and significantly accelerate the integration of myofibers into the collagen material at 90 d after surgery compared to the other two groups. Due to the replacement of the myofibers in materials, the mechanical strength of implanted biomaterials in collagen/CBD-bFGF group was also greater than the other two groups at 90 d after surgery. Thus, the collagen/CBD-bFGF composite biomaterial was promising for the treatment of full-thickness abdominal wall defect.

Biomechanical evaluation of microbial cellulose (Zoogloea sp.) and expanded polytetrafluoroethylene membranes as implants in repair of produced abdominal wall defects in rats

To evaluate the Load of Rupture of implants of membranes of microbial cellulose (Zoogloea sp.) and extended polytetrafuoroethylene in sharp defects of abdominal wall of rats. Sixty Wistar male rats, with a mean weight of 437,7 g +/- 40,9, anesthetized by a mixture of ketamine (5mg/100g) and xylazine (2mg/100g), were submitted to a rectangular (2 x 3 cm) excision of the abdominal wall, including fascia, muscle and peritoneum, and treated with membranes of microbial cellulose (MC) (MC Group- 30 animals) or extended polytetrafluoroethylene (ePTFE) (ePTFE Group- 30 animals). Each group was subdivided in 14th POD, 28th POD and 60th POD Subgroups. Under anesthesia, animals were submitted to euthanasia at 14th POD, 28th POD and 60th POD for evaluation of Load of Rupture. Load of Rupture levels were significantly elevated (p<0, 05) among 14th, 28th and 60th postoperative days from each Group. When compared between groups, values of Load of Rupture were significantly larger (p<0, 05) in ePTFE Group than in MC Group. Resistance to strength at implant/host interface was more pronounced in PTFEe Group than in MC Group.

In vitro and in vivo comparison of five biomaterials used for orthopedic soft tissue augmentation

To compare biomaterials used in orthopedics with respect to in vitro cell viability and cell retention and to in vivo tissue healing and regeneration. 65 adult female Sprague-Dawley rats and synovium, tendon, meniscus, and bone marrow specimens obtained from 4 adult canine cadavers. Synovium, tendon, meniscus, and bone marrow specimens were used to obtain synovial fibroblasts, tendon fibroblasts, meniscal fibrochondrocytes, and bone marrow-derived connective tissue progenitor cells for culture on 5 biomaterials as follows: cross-linked porcine small intestine (CLPSI), non-cross-linked human dermis, cross-linked porcine dermis, non-cross-linked porcine small intestine (NCLPSI), and non-cross-linked fetal bovine dermis. After 1 week of culture, samples were evaluated for cell viability, cell density, and extracellular matrix production. Biomaterials were evaluated in a 1-cm(2) abdominal wall defect in rats. Each biomaterial was subjectively evaluated for handling, suturing, defect fit, and ease of creating the implant at the time of surgery, then grossly and histologically 6 and 12 weeks after surgery. All biomaterials allowed for retention of viable cells in culture; however, CLPSI and NCLPSI were consistently superior in terms of cell viability and cell retention. Cell infiltration for NCLPSI was superior to other biomaterials. The NCLPSI appeared to be replaced with regenerative tissue most rapidly in vivo and scored highest in all subjective evaluations of ease of use. These data suggested that NCLPSI and CLPSI have favorable properties for further investigation of clinical application in orthopedic tissue engineering.

Resterilized Mesh in Repair of Abdominal Wall Defects in Rats

A variety of negative opinions about repeated usage of relatively expensive resterilized synthetic meshes have been considered. It had been stated that resterilized polypropylene meshes inhibits fibroblastic activity, decreases proliferative activity, and increases apoptosis in human fibroblast culture, in vitro. The purpose of this study is the in vivo evaluation of the resterilized mesh repairs of abdominal hernia defects in rat models of incisional hernia by comparing primer repair and original mesh repairs. The rats (n = 22) were separated into three groups. While the abdominal defect was repaired by primary suture in the control group (CG), the defects were repaired by original mesh (OG) or resterilized mesh (RG) in mesh-repaired groups. After 21 days, the rats were evaluated for tissue tensile strengths, tissue hydroxyproline levels, tissue inflammation, fibrosis, and apoptosis. Although the tensile strengths in OG and RG were significantly higher than those of CG (p <. 05 and p <. 05), there was no significant difference between two groups. The tissue hydroxyproline levels in OG and RG were also higher than those of CG. The difference was not significant between the two groups. The inflammation and fibrosis indexes in OG and RG were significantly higher than those of CG (p <. 0001 for both), but there was no difference between groups. While the apoptosis index in OG and RG was also higher than that of CG (p <. 0001 for both), there was no significant difference between OG and RG. The usage of resterilized mesh in abdominal wall repair did not reduce the tissue tensile strength, did not affect the tissue hydroxyproline levels, did not decrease the fibrosis, and did not increase the tissue inflammation and apoptosis. In conclusion, usage of resterilized meshes in abdominal wall defects was as safe as sterilized meshes.

Peritoneal Regeneration Induced by an Acellular Bovine Pericardial Patch in the Repair of Abdominal Wall Defects

This study was to evaluate the feasibility of using an acellular bovine pericardium fixed with genipin (AGP) to repair an abdominal wall defect created in a rat model. The glutaraldehyde-fixed acellular pericardium (AGA), the genipin-fixed cellular pericardium (GP), and a commercially available polypropylene mesh were used as controls. Gross examination at 3-month post-operatively revealed that dense adhesions to the visceral organs were observed for the polypropylene mesh and the AGA patch, while a filmy to dense adhesion was seen for the GP patch. In contrast, no adhesion to the visceral organs was observed for the AGP patch. Histologically, inflammatory cells were found mainly surrounding the GP patch. In contrast, host cells (inflammatory cells, fibroblasts, and neo-capillaries) were able to infiltrate into the AGA and AGP patches. Unlike the AGA patch, the AGP patch retrieved at 1-month post-operatively became well integrated with the host tissue near the suture line. Additionally, there were some mesothelial cells, identified by the van Gieson stain, observed on the AGP patch. At 3-month post-operatively, a neo-peritoneum was observed on the AGP patch. The neo-peritoneum consisted of organized vascularized connective tissues covered by an intact layer of mesothelial cells. The calcium contents of the polypropylene mesh and the AGA patch increased significantly at 3-month post-operatively, while those of the GP and AGP patches stayed minimal throughout the entire course of the study. The results obtained in the study revealed that the AGP patch effectively repaired abdominal wall defects in rats and successfully prevented the formation of post-surgical abdominal adhesions.

Tissue Regenerating Capacity of Carbodiimide-Crosslinked Dermal Sheep Collagen during Repair of the Abdominal Wall

In future, the function of collagen-based biomaterials as temporary scaffolds for the generation of new tissue may be emphasized. In this study the function of dermal sheep collagen (DSC) crosslinked with carbodiimide (ENDSC) as repair material for abdominal wall defects in rats was compared with that of commercial hexamethylenediisocyanate-crosslinked HDSC. The results indicate that early after implantation both ENDSC and HDSC functioned well as a matrix for cellular ingrowth. However during further implantation HDSC soon degraded resulting in herniations, while ENDSC showed a delay in the degradation time of at least 20 weeks. ENDSC thereby enabled collagen new-formation and functioned as a guidance for muscle overgrowth. These results are very promising concerning the problem of the ongoing foreign body reaction with continuing risk of implant rejection observed in clinical practice with non-degradable materials.