Robert Srnec

Central European Institute of Technology-Czech Republic, Brünn, South Moravian, Czech Republic

Are you Robert Srnec?

Claim your profile

Publications (26)16.69 Total impact

  • [Show abstract] [Hide abstract]
    ABSTRACT: PURPOSE OF THE STUDY Recent trends in the experimental surgical management of a partial anterior cruciate ligament (ACL) rupture in animals show repair of an ACL lesion using novel biomaterials both for biomechanical reinforcement of a partially unstable knee and as suitable scaffolds for bone marrow stem cell therapy in a partial ACL tear. The study deals with mechanical testing of the newly developed ultra-high-molecular-weight polyethylene (UHMWPE) biomaterial anchored to bone with Hexalon biodegradable ACL/PCL screws, as a new possibility of intra-articular reinforcement of a partial ACL tear. MATERIAL AND METHODS Two groups of ex vivo pig knee models were prepared and tested as follows: the model of an ACL tear stabilised with UHMWPE biomaterial using a Hexalon ACL/PCL screw (group 1; n = 10) and the model of an ACL tear stabilised with the traditional, and in veterinary medicine used, extracapsular technique involving a monofilament nylon fibre, a clamp and a Securos bone anchor (group 2; n = 11). The models were loaded at a standing angle of 100° and the maximum load (N) and shift (mm) values were recorded. RESULTS In group 1 the average maximal peak force was 167.6 ± 21.7 N and the shift was on average 19.0 ± 4.0 mm. In all 10 specimens, the maximum load made the UHMWPE implant break close to its fixation to the femur but the construct/fixation never failed at the site where the material was anchored to the bone. In group 2, the average maximal peak force was 207.3 ± 49.2 N and the shift was on average 24.1 ± 9.5 mm. The Securos stabilisation failed by pullout of the anchor from the femoral bone in nine out of 11 cases; the monofilament fibre ruptured in two cases. CONCLUSIONS It can be concluded that a UHMWPE substitute used in ex-vivo pig knee models has mechanical properties comparable with clinically used extracapsular Securos stabilisation and, because of its potential to carry stem cells and bioactive substances, it can meet the requirements for an implant appropriate to the unique technique of protecting a partial ACL tear. In addition, it has no critical point of ACL substitute failure at the site of its anchoring to the bone (compared to the previously used PET/PCL substitute). Key words: knee stabilisation, stifle surgery, ultra-high-molecular-weight polyethylene, UHMWPE, nylon monofilament thread, biodegradable screw, bone anchor.
    No preview · Article · Aug 2015 · Acta chirurgiae orthopaedicae et traumatologiae Cechoslovaca
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: The study deals with mechanical testing of newly developed material polyethylene terephtalate coated with polycaprolactone nanofibers in combination with biodagradable Hexalon ACL/PCL screws as a new possibility of intra-articular reinforcement of partially ruptured cranial cruciate ligament. Four groups of ex vivo models of pig stifle joints were prepared and tested: a model with intact CCL (group 1), a model with partial CCL rupture (group 2), a model with CCL rupture stabilized with 7 mm Mersilene® strip (group 3), and a model with CCL rupture stabilized with 5 mm PET/PCL biomaterial strip (group 4). The models were loaded in the standing angle of 100° and the maximum load (N) and the shift (mm) were monitored. The mean maximum peak power and the shift were 1266.0 ± 146.9 N and 13.7 ± 2.5 mm for group 1, and 1164.7 ± 228.2 N and 1 6.8 ± 3.3 mm for group 2, respectively. In all cases after reaching the maximum load, a tibial fracture occurred but never a CCL rupture. In groups 3 and 4, the initial fixation failure occurred in the mean values of 375.7 ± 81.5 and 360.4 ± 52.0 N, respectively, and with a bigger shift of 52.3 ± 11.9 mm and 39.4 ± 14.6 mm, respectively, compared to group 1. A critical point of failure was the anchoring in the bone. It can be concluded that the PET/PCL substitute in the ex vivo model has mechanically comparable properties with the clinically used Mersilene®, and based on its proven ability to carry stem cells it could be appropriate for partially ruptured CCL protection.
    Preview · Article · Mar 2014 · Acta Veterinaria Brno
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: The outcomes of six different surgical techniques of caudal cervical spondylomyelopathy treatment in dogs with static and dynamic spinal cord compressions were assessed. Out of 425 dogs with cervical spine diseases, caudal cervical spondylomyelopathy was diagnosed in 69 dogs. Dynamic myelographic study was performed in 48 of them as a diagnostic method necessary for choosing the appropriate technique of surgical treatment. Twenty-five out of the 48 dogs underwent surgery. The best results of the surgical treatment of static compression were achieved with a ventral slot (89% of the nine surgical interventions) with partial improvement 48 h after surgery and marked improvement 8 weeks after surgery. For dynamic compressions, vertebral traction and stabilization with intervertebral washer plus vertebral body screws and polymethylmethacrylate bridge was found to be the most successful surgical treatment with significant improvement in 62% of the thirteen surgical interventions 8 weeks after surgery. In 5 dogs (20%), two intervertebral spaces with caudal cervical spondylomyelopathy were surgically treated. Recurrence was observed in 6 dogs (24%) after the mean period of 20 months (5 to 44 months) after surgery. Direct ventral slot decompression could be recommended for clinical cases of the caudal cervical spondylomyelopathy with static compression, and intervertebral washer plus vertebral body screws and polymethylmethacrylate bridge for dogs with dynamic compression, respectively. Our findings refer to the results of surgical treatment in a relatively large number of dogs with caudal cervical spondylomyelopathy and can help surgeons to choose an effective surgical method of treatment in dogs with wobbler syndrome based on dynamic myelographic study findings.
    Preview · Article · Dec 2012 · Acta Veterinaria Brno
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: The study deals with the possibility of substituting time- and material-demanding mechanical testing of a bone defect fixation by mathematical modelling. Based on the mechanical model, a mathematical model of bone-implant construct stabilizing experimental segmental femoral bone defect (segmental ostectomy) in a miniature pig ex vivo model using 4.5 mm titanium LCP was created. It was subsequently computer-loaded by forces acting parallel to the long axis of the construct. By the effect of the acting forces the displacement vector sum of individual construct points occurred. The greatest displacement was noted in the end segments of the bone in close proximity to ostectomy and in the area of the empty central plate hole (without screw) at the level of the segmental bone defect. By studying the equivalent von Mises stress σEQV on LCP as part of the tested construct we found that the greatest changes of stress occur in the place of the empty central plate hole. The distribution of this strain was relatively symmetrical along both sides of the hole. The exceeding of the yield stress value and irreversible plastic deformations in this segment of LCP occurred at the acting of the force of 360 N. These findings are in line with the character of damage of the same construct loaded during its mechanic testing. We succeeded in creating a mathematical model of the bone-implant construct which may be further used for computer modelling of real loading of similar constructs chosen for fixation of bone defects in both experimental and clinical practice.
    Preview · Article · Sep 2012 · Acta Veterinaria Brno
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: This study describes the results achieved using a combination of allogeneic mesenchymal stem cells (MSCs) with chondrocytes (CHC) and a new scaffold consisting of type-I collagen and chitosan nanofibers in the prevention of partial growth plate arrest after iatrogenic injury in pigs. The miniature pig was selected as an experimental model to compare the results in the left femoral bones (MSCs and CHC in scaffold transplantation into the iatrogenic partial distal growth plate defect) and right femoral bones (scaffold alone transplantation). The experimental group consisted of 10 animals. Bone marrow from os ilium as the source of MSCs was used. A porous cylinder consisting of 0.5% by weight type-I collagen and 30% by weight chitosan, was the optimal choice. The length of the bone and angular deformity of distal femur after the healing period was measured and the quality and structure of the newly formed cartilage was histologically examined. Transplantation of the composite scaffold in combination with MSCs and chondrocytes led to the prevention of growth disorder and angular deformity in the distal epiphysis of the left femur. Compared to the right (control) femur, tissue similar to hyaline cartilage with signs of columnar organization typical of the growth plate occurred in most cases. The promising results of this study reveal the new and effective means for the prevention of bone bridge formation after growth plate injury.
    Preview · Article · Jun 2012 · Biomedical papers of the Medical Faculty of the University Palacky, Olomouc, Czechoslovakia
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: The aim of the study was to detect and compare the haemostatic variables and bleeding after 7-days administration of carprofen or meloxicam in clinically healthy miniature pigs. Twenty-one clinically healthy Gottingen miniature pigs were divided into 3 groups. Selected haemostatic variables such as platelet count, prothrombin time, activated partial thromboplastin time, thrombin time, fibrinogen, serum biochemical variables such as total protein, bilirubin, urea, creatinine, alkaline phosphatase, alanine aminotransferase and gamma-glutamyltransferase and haemoglobin, haematocrit, red blood cells, white blood cells and buccal mucosal bleeding time were assessed before and 7 days after daily intramuscular administration of saline (1.5 ml per animal, control group), carprofen (2 mg.kg(-1)) or meloxicam (0.1 mg.kg(-1)). In pigs receiving carprofen or meloxicam, the thrombin time was significantly increased (p < 0.01) compared to the control group. In animals receiving carprofen, serum urea and creatinine were significantly decreased, compared to the control (p < 0.01) or meloxicam (p < 0.05) groups. In pigs receiving meloxicam, serum urea was significantly decreased (p < 0.05) compared to the control group. Significant differences were not detected in other haemostatic, biochemical variables or bleeding time compared to other groups or to the pretreatment values. Intramuscular administration of carprofen or meloxicam in healthy miniature pigs for 7 days causes sporadic, but not clinically important changes of selected haemostatic variables. Therefore, we can recommend them for perioperative use, e.g. for their analgesic effects, in orthopaedic or other surgical procedures without increased bleeding.
    Preview · Article · Dec 2011 · Acta Veterinaria Brno
  • [Show abstract] [Hide abstract]
    ABSTRACT: To quantify humeroulnar incongruity on elbow radiographs in Labrador Retrievers with or without medial coronoid disease (MCD). Retrospective study of 92 elbows. Radiographic projections of elbow joints from Labrador Retrievers with MCD (n = 42 elbows; 26 dogs) and without MCD (n = 50 elbows; 25 dogs). The congruity of the humeroulnar joint was measured using an index of subluxation (SI) for each elbow. SI was defined as the distance between the centers of 2 circles drawn along the margins of the incisura trochlearis and the trochlea of humerus on mediolateral digital radiographic projections, normalized by the radius of the circle circumscribing the humeral trochlea. SI was compared between right and left elbows with and without pathology using a Wilcoxon test for paired data, and between normal and abnormal groups with a Wilcoxon test for unpaired data. Mismatch between ulnar curvature and curvature of humeral trochlea and radioulnar incongruency were also noted (Wilcoxon test). The intraobserver repeatability, correlation between SI and radioulnar incongruency, and between SI and mismatch elbow curvature were estimated with a Pearson's correlation coefficient. Intraobserver repeatability of SI measurement was high (r = 0.97). Mean ± SD humeroulnar incongruity (SI) was greater in elbows with MCD (18.5 ± 6.6) than in the normal elbows (1.7 ± 2.0, P < 0.001). The difference between the diameters of the curvatures of the ulnar and humeral trochlea was greater in elbows with MCD (12.5 ± 4.4) than in the normal group (10.7 ± 4.1, P < 0.05). A moderate correlation was found between the degree of humeroulnar incongruity and a radioulnar step (r = 0.63); however, no correlation was identified between SI and the difference between the diameters of the curvatures of the ulnar and humeral trochleae (r = 0.14). We propose a radiographic index to measure humeroulnar incongruity on mediolateral digital radiographic projections. This index (SI) supports the presence of humeroulnar incongruity in Labrador Retrievers with MCD. Further evaluation of its reproducibility and clinical importance are warranted. Although there is a moderate correlation between humeroulnar incongruity and radioulnar incongruency, causation has not been established.
    No preview · Article · Oct 2011 · Veterinary Surgery
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: At present, attention is focused on research into possibilities of healing large bone defects by the method of mini-invasive osteosynthesis, using implantation of biomaterials and mesenchymal stem cells (MSCs). This study evaluates the healing of segmental femoral defects in miniature pigs based on the radiological determination of the callus: cortex ratio at 16 weeks after ostectomy. The size of the formed callus was significantly larger (p < 0.05) in animals after transplantation of an autogenous cancellous bone graft (group A, callus : cortex ratio of 1.77 +/- 0.33) compared to animals after transplantation of cylindrical scaffold from hydroxyapatite and 0.5% collagen (group S, callus : cortex ratio of 1.08 +/- 0.13), or in animals after transplantation of this scaffold seeded with MSCs (group S + MSCs, callus: cortex ratio of 1.15 +/- 0.18). No significant difference was found in the size of callus between animals of group S and animals of group S + MSCs. Unlike a scaffold in the shape of the original bone column, a freely placed autogenous cancellous bone graft may allow the newly formed tissue to spread more to the periphery of the ostectomy defect. Implanted cylindrical scaffolds (with and without MSCs) support callus formation directly in the center of original bone column in segmental femoral ostectomy, and can be successfully used in the treatment of large bone defects.
    Full-text · Article · Dec 2010 · Acta Veterinaria Brno
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: The study describes types, absolute and relative numbers of implant failures in flexible bridging osteosynthesis using a six-hole 3.5 mm titanium Locking Compression Plate (n = 9) or a five-hole LCP 4.5 mm titanium (n = 40) selected for the fixation of segmental ostectomy of femoral diaphysis in the miniature pig used as an in vivo model in a study on the healing of a critically sized bone defect using transplantation of mesenchymal stem cells combined with biocompatible scaffolds within a broader research project. Occasional implant failure was evaluated based on radiographic examination of femurs of animals 2, 4, 8, 12 and 16 weeks after surgery. When bone defect was stabilized using 3.5 mm LCP, in 6 cases (66.7%) the screw was broken/lost in the proximal fragment of the femur 2 weeks after implantation (n = 4) and 4 weeks after implantation (n = 2). In 4 cases of these, the implant failure was accompanied also by loosening of the screw in position 3 in the proximal fragment of the femur. During ostectomy stabilization with 4.5 mm LCP, in 3 cases (7.5%) LCP was broken at the place of the empty central plate hole (without inserted screw) at the level of the segmental bone defect. Compared to the six-hole 3.5 mm LCP, the five-hole titanium 4.5 mm LCP is more suitable implant for flexible bridging osteosynthesis of a critically sized segmental defect of femoral diaphysis in the miniature pig. The results of this study will allow reducing implant failures in time-and cost-demanding transplantation experiments focused on bone healing.
    Preview · Article · Dec 2010 · Acta Veterinaria Brno
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: The study deals with the determination of mechanical properties, namely resistance to bending forces, of flexible buttress osteosynthesis using two different bone-implant constructs stabilizing experimental segmental femoral bone defects (segmental ostectomy) in a miniature pig ex vivo model using 4.5 mm titanium LCP and a 3 mm intramedullary pin ("plate and rod" construct) (PR-LCP), versus the 4.5 mm titanium LCP alone (A-LCP). The "plate and rod" fixation (PR-LCP) of the segmental femoral defect is significantly more resistant (p < 0.05) to bending forces (200 N, 300 N, and 500 N) than LCP alone (A-LCP). Stabilisation of experimental segmental lesions of the femoral diaphysis in miniature pigs by flexible bridging osteosynthesis 4.5 mm LCP in combination with the "plate and rod" construct appears to be a suitable fixation of non-reducible fractures where considerable strain of the implants by bending forces can be assumed. These findings will be used in upcoming in vivo experiments in the miniature pig to investigate bone defect healing after transplantation of mesenchymal stem cells in combination with biocompatible scaffolds.
    Preview · Article · Dec 2010 · Acta Veterinaria Brno
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: The aim of the study was to find the frequency of radiologically detectable kissing lesion in individual variants of fragmented processus coronoideus medians (FCP) and its occurrence in relation to sex The radiographs of elbow joints (n = 135) of dogs (n = 77) in which a fragmented processus coronoideus medians ulnae was detected arthroscopically (n = 109) or arthrotomically (n = 26) were evaluated Significantly higher occurrence of radiologically detectable kissing lesion was found in elbows with non dislocated and dislocated fragment (p < 0 01) Significantly lower occurrence of radiologically detectable kissing le,,ion was found in elbows with chondromalacia of processus coronoideus medians (PCM) (p < 0 01) We found no significant difference (p > 0 05) between the occurrence of a kissing lesion in males and females with FCP The occurrence of the kissing lesion extending to the subchondral bone was not affected by sex The results of our study suggest the possibility of identifying elbow joints with completely fragmented FCP on the basis of occurrence of a radiologically detectable kissing lesion
    Preview · Article · Nov 2010 · Acta Veterinaria Brno
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: The aim of the study was to find whether there is a difference in the optical density of the subtrochlear region of incisura trochlearis and in the region of processus coronoideus medialis ulnae in elbow joints with fragmented processus coronoideus and in healthy elbow joints of the Labrador retriever breed. We evaluated digital radiographs of elbows (n = 26) with arthroscopically or arthrotomically proven FCP and digital radiographs of healthy elbows (n = 28). A template was made on radiographs in the JiveX program (Visus Technology Transfer) demarcating individual regions of interest (ROI) in which median optical density was measured. For normalisation of median optical density data of individual ROI, median optical density of the caudal ulnar cortex was used. Elbow joints with fragmented processus coronoideus had a lower mean median optical density in the distal part of incisura trochlearis compared to healthy elbow joints. The lowest median optical densities were found in the region of processus coronoideus medialis and in the distal part of the trochlear notch of the ulna in the region of processus coronoideus lateralis. The biggest difference in median optical densities between elbows with FCP and healthy elbows was found in regions distant from the articular surface. In evaluation of the opacity of the trochlear notch of the ulna it is appropriate to assess the whole region of the proximal ulnar metaphysis from the articular surface to the caudal ulnar cortex.
    Preview · Article · Jun 2010 · Acta Veterinaria Brno
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: The aim of the study was to find the difference between actual and anticipated frequencies of individual types of FCP (fragmented coronoid process) in relation to the extent of radioulnar incongruity. We evaluated the radiographs of elbow joints (n = 135) of dogs (n = 77) with arthroscopically (n = 109) or arthrotomically (n = 26) proven fragmented coronoideus medialis ulnae. Radioulnar incongruity was classified as a congruent joint (0-0.5 mm), moderate incongruity (0.6-2 mm) and marked incongruity (> 2.1 mm). In elbow joints without radiologically identifiable radioulnar incongruity (0-0.5 mm) significantly higher occurrence of fissured PCM (processus coronoideus medialis) was found (p < 0.01). In elbow joints with pronounced radioulnar incongruity (> 2.1 mm) we found significantly higher occurrence of FCP with a dislocated fragment (p < 0.001). The results of this study suggest the possibility of using the assessment of radioulnar incongruity from radiographs of elbow joints in mediolateral projection for specifying the X-ray diagnosis of FCP with regard to the type of FCP lesion.
    Full-text · Article · Jun 2010 · Acta Veterinaria Brno
  • P. Rauser · L. Stehlik · P. Proks · R. Srnec · A. Necas
    [Show abstract] [Hide abstract]
    ABSTRACT: Carprofen or meloxicam are nonsteroidal anti-inflammatory drugs (NSAIDs), which may elicit a variety of renal disturbances. Prior to this study, the effects of carprofen or meloxicam on renal function in pigs were unknown. A total of 21 clinically healthy Goettingen miniature pigs (36.9 ± 7.22 kg) were divided into three groups based on what they were administered - carprofen, meloxicam or saline. First, blood was collected from the jugular vein and urine by ultrasound-guided cystocentesis. Serum urea (U) and creatinine (CR), fractional clearance of sodium (FCNa), urine gamma-glutamyltransferase (GGT) and alkaline phosphatase (ALP) activities, urine protein/creatinine ratio (UP/UC), urine gamma-glutamyltransferase/creatinine ratio (GGT/CR) and urine alkaline phosphatase/creatinine ratio (ALP/CR) and urine analysis - urine specific gravity (USG) and sediment microscopy were assessed before and seven days after daily intramuscular administration (IM) of saline (1.5 ml per animal), carprofen (2 mg/kg) or meloxicam (0.1 mg/kg). All animals had identical housing, feeding and unlimited water intake and had not undergone surgery or been administered any medication for three months prior to this. All pigs served as control groups for an experimental study of fracture healing using transplantation of mesenchymal stem cells and scaffolds. The data were analyzed using a one way ANOVA and a Mann-Whitney test (P < 0.05). In pigs receiving carprofen, serum urea and creatinine were significantly decreased, compared to the control (P < 0.01) or meloxicam (P < 0.05) groups. In animals receiving meloxicam FCNa was significantly increased (P < 0.05) and urine specific gravity significantly decrease (P < 0.05) compared to the pretreatment values. Two carprofen-treated pigs had a slight increase in renal tubular epithelial cells upon urine sediment examination. Intramuscular administration of carprofen or meloxicam in healthy miniature pigs for seven days causes no clinically important changes in selected renal parameters (without azotemia). However these changes indicate mild damage of renal tubules. Despite these findings, meloxicam or carprofen are recommended for analgesia in healthy pigs.
    No preview · Article · Jan 2010 · Veterinární medicína
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: To compare the incidence of seizures in dogs with intervertebral disk disease after iopamidol or iomeprol myelography, and to assess whether the incidence of seizures differed between the 2 agents when severity of neurological deficits, location of cord compression, duration of anesthesia, site of myelogram, volume of contrast, and concentration of contrast were evaluated. Retrospective study. Veterinary teaching hospital. One hundred and sixty-one client-owned dogs with intervertebral disk disease. Subarachnoid injection of contrast medium. One hundred and sixty-one dogs with intervertebral disk disease were subjected to myelography using iopamidol (n=74) or iomeprol (n=87). Cranial myelography was performed in 31 dogs, caudal myelography in 125 and both cranial and caudal myelography in 5. Seizures occurred in 23 of 161 (14%) dogs. There was no significant difference overall between iopamidol and iomeprol myelography. However, in dogs with thoracolumbar disk extrusion and paraplegia, seizures occurred more frequently after caudal myelography using iopamidol compared with iomeprol. Both iomeprol and iopamidol are suitable for myelography in dogs. Iomeprol is recommended for caudal myelography in paraplegic dogs with thoracolumbar disk extrusion due to the higher incidence of seizures in this group when iopamidol was used.
    Full-text · Article · Dec 2009
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: This synoptic study gives a concise overview of current knowledge of bone healing, the role of mesenchymal stem cells in bone tissue regeneration and contemporary possibilities of supporting regeneration of damaged bone. Attention of research concerning the healing of fractures with extensive loss of bone tissue following trauma, the treatment of belatedly healing or non-healing fractures or the healing of segmental bone defects following tumour resection, is focused on development of three-dimensional scaffolds planted with mesenchymal stem cells that might be used for reconstruction of such large bone lesions. Presented are possibilities of transplantation of mesenchymal stem cells combined with biomaterials into bone defects, including the results of our own experimental studies dealing with the use of stem cells in the treatment of damaged tissues of the musculoskeletal system in animal models.
    Full-text · Article · Dec 2009 · Acta Veterinaria Brno
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Synthesis and characterization of biodegradable hydrogels based on collagen modified by addition of synthetic biodegradable copolymer intended for preparation of porous scaffolds for mesenchymal stem cells used for possible implantation to animals with articular surface defects was investigated. The synthetic biodegradable tri-block copolymer used was the block copolymer of polyethylene glycol (PEG), polylactic acid (PLA), polyglycolic acid (PGA) (PEG-PLGA) endcapped with itaconic acid (ITA). The water-soluble carbodiimide and N-hydroxysuccimide system (EDC-NHS) was chosen as the cross-linking agent used to control the rate of hydrogel resorption. Dependence of the physical properties of the prepared hydrogels on the concentration of the EDC-NHS cross-linker, reaction time and concentration of PEG-PLGA-ITA copolymer was examined. Swelling behaviour, thermal stability, surface morphology and degradation rate were also characterized. Based on the obtained results, it can be concluded that increase in concentration of the cross-linking agent, as well as prolonged cross-linking time and increased amount of synthetic copolymer lead to enhanced thermal stability of the gels together with a reduced swelling ratio and degradation rate in saline. The resorption rate of these gels used in preparation of cartilage scaffolds can be controlled over a wide time interval by varying the collagen/(PEG-PLGA-ITA) blend composition or the conditions of the cross-linking reaction.
    Full-text · Article · Dec 2009 · Acta Veterinaria Brno
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: The aim of this study was to evaluate macroscopically, histologically and immunohistochemically the quality of newly formed tissue in iatrogenic defects of articular cartilage of the femur condyle in miniature pigs treated with the clinically used method of microfractures in comparison with the transplantation of a combination of a composite scaffold with allogeneic mesenchymal stem cells (MSCs) or the composite scaffold alone. The newly formed cartilaginous tissue filling the defects of articular cartilage after transplantation of the scaffold with MSCs (Group A) had in 60 % of cases a macroscopically smooth surface. In all lesions after the transplantation of the scaffold alone (Group B) or after the method of microfractures (Group C), erosions/fissures or osteophytes were found on the surface. The results of histological and immunohistochemical examination using the modified scoring system according to O'Driscoll were as follows: 14.7+/-3.82 points after transplantations of the scaffold with MSCs (Group A); 5.3+/-2.88 points after transplantations of the scaffold alone (Group B); and 5.2+/-0.64 points after treatment with microfractures (Group C). The O'Driscoll score in animals of Group A was significantly higher than in animals of Group B or Group C (p<0.0005 both). No significant difference was found in the O'Driscoll score between Groups B and C. The treatment of iatrogenic lesions of the articular cartilage surface on the condyles of femur in miniature pigs using transplantation of MSCs in the composite scaffold led to the filling of defects by a tissue of the appearance of hyaline cartilage. Lesions treated by implantation of the scaffold alone or by the method of microfractures were filled with fibrous cartilage with worse macroscopic, histological and immunohistochemical indicators.
    Full-text · Article · Nov 2009 · Physiological research / Academia Scientiarum Bohemoslovaca
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: The aim of the study was to verify whether there is a difference in the lengthwise growth of the femurs and in their angular deformity when comparing preventive vs. therapeutic transplantation of allogeneic mesenchymal stem cells (MSCs) to an iatrogenic defect in the distal physis of femur. Modified composite chitosan/collagen type I scaffold with MSCs was transplanted to an iatrogenically created defect of the growth cartilage in the lateral condyle of the left femur in 20 miniature male pigs. In Group A of animals (n = 10) allogeneic MSCs were transplanted immediately after creating the defect in the distal physis of femur (preventive transplantation). In Group B of animals (n = 10) the same defect of the growth cartilage was treated by transplantation of allogeneic MSCs four weeks after its creation (therapeutic transplantation), after the excision of the bone bridge that had formed in it. On average, left femurs with a damaged distal physis and preventively transplanted allogeneic MSCs (Group A) grew during 4 months from transplantation by 0.56 ± 0.44 cm more than right femurs without the transplantation of MSCs, whereas left femurs with physeal defects treated with a therapeutic transplantation of allogeneic MSCs (Group B) by 0.14 ± 0.72 cm only, compared to right femurs without transplanted MSCs. Four months after preventive transplantation of MSCs (Group A), valgus deformity of the distal part of left femur with the defect was 0.78 ± 0.82°; in the control group (right femur in the same animal without MSCs transplantation) it was 3.7 ± 0.82°. After therapeutic transplantation of MSCs (Group B) 0.6 ± 3.4°, in the control group (right femur in the same animal without MSCs transplantation) it was 2.1 ± 2.9°. In all the animals of Groups A and B, the presence of newly formed hyaline cartilage was confirmed histologically and immunohistochemically. In the distal physis of right femurs with an iatrogenic defect of the growth cartilage without the transplantation of MSCs (control) bone bridge was formed. Preventive transplantation of allogeneic MSCs into the defect of the distal growth zone of femur appears more suitable compared to the therapeutic transplantation, with regard to the more pronounced lengthwise bone growth. Differences found in the extent of valgus deformity were non-significant comparing preventive and therapeutic transplantations of MSCs. MSCs, growth plate, deformity, bone bridge Injury of the growth cartilage of the long bones of the extremities usually leads to the formation of a bone bridge between epiphysis and metaphysis of the long bone (Key and Ford 1958; Bright 1974). At the same time, in approximately 25 - 30% of cases the lengthwise bone growth is reduced and its angular deformity occurs (Ahn et al. 2004). Besides, in 10% of these cases, the function of the relevant joint is impaired (Mann and
    Preview · Article · Jun 2009 · Acta Veterinaria Brno
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: This study appears from an experiment previously carried out in New Zealand white rabbits. Allogenic mesenchymal stem cells (MSCs) were transplanted into an iatrogenically-created defect in the lateral section of the distal physis of the left femur in 10 miniature pigs. The right femur with the same defect served as a control. To transfer MSCs, a freshly prepared porous scaffold was used, based on collagen and chitosan, constituting a compact tube into which MSCs were implanted. The pigs were euthanized four months after the transplantation. On average, the left femur with transplanted MSCs grew more in length (0.56+/-0.14 cm) compared with right femurs with physeal defect without transplanted MSCs (0.14+/-0.3 cm). The average angular (valgus) deformity of the left femur had an angle point of 0.78 degrees , following measurement and X-ray examination, whereas in the right femur without transplantation it was 3.7 degrees. The initial results indicate that preventive transplantation of MSCs into a physeal defect may prevent valgus deformity formation and probably also reduce disorders of the longitudinal bone growth. This part of our experiment is significant in the effort to advance MSCs application in human medicine by using pig as a model, which is the next step after experimenting on rabbits.
    Full-text · Article · Jan 2009 · Physiological research / Academia Scientiarum Bohemoslovaca

Publication Stats

136 Citations
16.69 Total Impact Points

Institutions

  • 2014
    • Central European Institute of Technology-Czech Republic
      Brünn, South Moravian, Czech Republic
  • 2007-2012
    • University of Veterinary and Pharmaceutical Sciences Brno
      • Faculty of Veterinary Medicine
      Brünn, South Moravian, Czech Republic
  • 2008
    • Brno University of Technology
      • Institute of Materials Chemistry "IMC"
      Brünn, South Moravian, Czech Republic