RESUMO
The novel personal protection equipment based on a face mask equipped with a nanofiber filter functionalized with povidone iodine has been developed and tested in a clinical trial. This nanofiber filter was characterized with a low flow resistance and, thus, allowed comfortable breathing. The performed study proved that the novel nanofiber filter with incorporated povidone-iodine was characterized with a slow release of iodine which minimized side effects but kept disinfection efficiency. Our clinical study performed on 207 positively tested SARS-CoV-2 patients wearing the PPE for 4-8 hours daily for 1 to 4 days has shown that even the iodine amount as low as 0.00028 ppm was sufficient to significantly decrease the reproduction number and, very importantly, to protect against severe course of disease.
Assuntos
COVID-19 , Nanofibras , Povidona-Iodo , SARS-CoV-2 , Povidona-Iodo/uso terapêutico , Povidona-Iodo/administração & dosagem , COVID-19/prevenção & controle , Humanos , Pandemias/prevenção & controle , Pneumonia Viral/prevenção & controle , Infecções por Coronavirus/prevenção & controle , Betacoronavirus , Anti-Infecciosos Locais/administração & dosagem , Masculino , Feminino , Adulto , Máscaras , Equipamento de Proteção Individual , Pessoa de Meia-IdadeRESUMO
Wound healing is a dynamic process involving different cell types with distinct roles according to the stages of healing. Fibroblasts and stem cells actively participate in tissue regeneration. A proper stimulation could contribute to enhance wound healing process-es. Helichrysum italicum (H. italicum) is a medical plant well described for its pharmacological, antimicrobial, and anti-inflammatory activities. Aim of the present work was to examine the effect of the hydrolat derivate from H. italicum on stem cells isolated from skin and fibroblasts in vitro in presence or absence of tissue damage. The viability and proliferation of all cell types cultured in dif-ferent conditions were analyzed by MTT and BrdU assays. Cell proliferation after wound was analyzed with scratch test. Also, the expression of the main genes involved in tissue repair was evaluated by RT-qPCR analysis. Here we describe the capability of hy-drolat of H. italicum to promote tissue regeneration after scratch test both in stem cells and in fibroblasts. Moreover, the gene ex-pression analysis revealed that, hydrolat of H. italicum is also able to enhance stemness related. In conclusion our results are en-couraging, highlighting novel regenerative properties of hydrolat of H. italicum and paving the way for future application of this wasting product in accelerating wound healing.
Assuntos
Helichrysum , Cicatrização , Pele , Anti-Inflamatórios/farmacologia , Células-Tronco , Fibroblastos/metabolismoRESUMO
BACKGROUND: Surgical mesh is widely used not only to treat but also to prevent incisional hernia formation. Despite much effort by material engineers, the 'ideal' mesh mechanically, biologically and surgically easy to use remains elusive. Advances in tissue engineering and nanomedicine have allowed new concepts to be tested with promising results in both small and large animals. Abandoning the concept of a pre-formed mesh completely for a 'pour in liquid mesh' has never been tested before. MATERIALS AND METHODS: Thirty rabbits underwent midline laparotomy with closure using an absorbable suture and small stitch small bites technique. In addition, their abdominal wall closure was reinforced by a liquid nanofibrous scaffold composed of a fibrin sealant and nanofibres of poly-ε-caprolactone with or without hyaluronic acid or the sealant alone, poured in as an 'onlay' over the closed abdominal wall. The animals were killed at 6 weeks and their abdominal wall was subjected to histological and biomechanical evaluations. RESULTS: All the animals survived the study period with no major complication. Histological evaluation showed an eosinophilic infiltration in all groups and foreign body reaction more pronounced in the groups with nanofibres. Biomechanical testing demonstrated that groups treated with nanofibres developed a scar with higher tensile yield strength. CONCLUSION: The use of nanofibres in a liquid form applied to the closed abdominal wall is easy to use and improves the biomechanical properties of healing fascia at 6 weeks after midline laparotomy in a rabbit model.
Assuntos
Parede Abdominal , Hérnia Incisional , Nanofibras , Parede Abdominal/cirurgia , Animais , Herniorrafia/métodos , Humanos , Hérnia Incisional/cirurgia , Coelhos , Telas Cirúrgicas/efeitos adversos , Técnicas de Sutura/efeitos adversosRESUMO
Non-woven textile mesh from polyglycolic acid (PGA) was found as a proper material for chondrocyte adhesion but worse for their proliferation. Neither hyaluronic acid nor chitosan nor polyvinyl alcohol (PVA) increased chondrocyte adhesion. However, chondrocyte proliferation suffered from acidic byproducts of PGA degradation. However, the addition of PVA and/or chitosan into a wet-laid non-woven textile mesh from PGA improved chondrocyte proliferation seeded in vitro on the PGA-based composite scaffold namely due to a diminished acidification of their microenvironment. This PVA/PGA composite mesh used in combination with a proper hydrogel minimized the negative effect of PGA degradation without dropping positive parameters of the PGA wet-laid non-woven textile mesh. In fact, presence of PVA and/or chitosan in the PGA-based wet-laid non-woven textile mesh even advanced the PGA-based wet-laid non-woven textile mesh for chondrocyte seeding and artificial cartilage production due to a positive effect of PVA in such a scaffold on chondrocyte proliferation.
Assuntos
Condrócitos/citologia , Ácido Poliglicólico , Álcool de Polivinil , Técnicas de Cultura de Tecidos/métodos , Alicerces Teciduais , Animais , Cartilagem/citologia , Adesão Celular , Divisão Celular , Ácido Hialurônico , Hidrogel de Polietilenoglicol-Dimetacrilato , Microscopia Confocal , Coelhos , Têxteis , ÁguaRESUMO
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.
Assuntos
Cartilagem Articular/cirurgia , Quitosana/metabolismo , Condrogênese , Colágeno Tipo I/metabolismo , Traumatismos do Joelho/cirurgia , Articulação do Joelho/cirurgia , Transplante de Células-Tronco Mesenquimais , Nanofibras , Alicerces Teciduais , Animais , Artroplastia Subcondral , Cartilagem Articular/lesões , Cartilagem Articular/metabolismo , Cartilagem Articular/patologia , Células Cultivadas , Modelos Animais de Doenças , Imuno-Histoquímica , Traumatismos do Joelho/metabolismo , Traumatismos do Joelho/patologia , Articulação do Joelho/metabolismo , Articulação do Joelho/patologia , Suínos , Porco Miniatura , Fatores de Tempo , CicatrizaçãoRESUMO
Molecular modeling of the H4-H5-loop of the alpha2 isoform of Na+/K+-ATPase in the E1 and E2 conformations revealed that twisting of the nucleotide (N) domain toward the phosphorylation (P) domain is connected with the formation of a short pi-helix between Asp369 and Thr375. This conformational change close to the hinge region between the N-domain and the P-domain could be an important event leading to a bending of the N-domain by 64.7 degrees and to a shortening of the distance between the ATP binding site and the phosphorylation site (Asp369) by 1.22 nm from 3.22 nm to 2.00 nm. It is hypothesized that this shortening mechanism is involved in the Na+-dependent formation of the Asp369 phospho-intermediate as part of the overall Na+/K+-ATPase activity.
Assuntos
Ácido Aspártico/química , ATPase Trocadora de Sódio-Potássio/química , Treonina/química , Ácido Aspártico/genética , Sítios de Ligação , Cinética , Modelos Moleculares , Isoformas de Proteínas/química , Isoformas de Proteínas/metabolismo , Estrutura Secundária de Proteína , ATPase Trocadora de Sódio-Potássio/genética , ATPase Trocadora de Sódio-Potássio/metabolismo , Treonina/genéticaRESUMO
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.
Assuntos
Fraturas do Fêmur/cirurgia , Fêmur/cirurgia , Fixação de Fratura/métodos , Desigualdade de Membros Inferiores/prevenção & controle , Transplante de Células-Tronco Mesenquimais , Osteogênese , Animais , Células Cultivadas , Modelos Animais de Doenças , Fraturas do Fêmur/diagnóstico por imagem , Fraturas do Fêmur/fisiopatologia , Fêmur/diagnóstico por imagem , Fêmur/crescimento & desenvolvimento , Fixação de Fratura/efeitos adversos , Desigualdade de Membros Inferiores/diagnóstico por imagem , Desigualdade de Membros Inferiores/etiologia , Desigualdade de Membros Inferiores/fisiopatologia , Transplante de Células-Tronco Mesenquimais/efeitos adversos , Radiografia , Suínos , Porco Miniatura , Fatores de Tempo , Alicerces Teciduais , Transplante AutólogoRESUMO
Pelvic surgeries such as extirpation of the rectum or pelvic exenteration lead to a creation of a dead space, which can be cause of complication, such as bowel obstruction, perineal hernia, abscess or hematoma. A growing incidence of complication is expected in connection with the increasing use of laparoscopic and robotic approaches or ELAPE method. Since the bone structures do not allow compression, the only way to deal with the dead space is to fill it in. Present methods provide the filling with omental or myofascial flaps. The length and the mobility of the omental flap can be the limitation. Myofascial flaps are technically more demanding and bring the complications of a donor place. Synthetic or biological meshes do not deal with dead space problematic. Modern technologies using nanomaterials offer the possibility to produce a material with specific properties for example shape, inner structure, surface, or time of degradation. The modified material could also satisfy the requirements for filling the dead space after surgeries.
Assuntos
Pelve/cirurgia , Complicações Pós-Operatórias/prevenção & controle , Reto/cirurgia , Materiais Biocompatíveis , HumanosRESUMO
PURPOSE: Incisional hernia is the most common complication following abdominal surgery. While mesh repair is common, none of the current meshes mimic the physiology of the abdominal wall. This study compares suture only repair with polypropylene mesh and a prototype of a novel implant (poly-epsilon-caprolactone nanofibers) and their influence on the physiology of an abdominal wall in an animal model. METHODS: 27 Chinchilla rabbits were divided into six groups based on the type of the implant. Midline abdominal incision was repaired using one of the compared materials with suture alone serving as the control. 6 weeks post-surgery animals were killed and their explanted abdominal wall subjected to biomechanical testing. RESULTS: Both-hysteresis and maximum strength curves showed high elasticity and strength in groups where the novel implant was used. Polypropylene mesh proved as stiff and fragile compared to other groups. CONCLUSION: Poly-epsilon-caprolactone nanofiber scaffold is able to improve the dynamic properties of healing fascia with no loss of maximum tensile strength when compared to polypropylene mesh in an animal model.
Assuntos
Abdominoplastia/instrumentação , Hérnia Abdominal , Herniorrafia/instrumentação , Hérnia Incisional , Nanofibras/uso terapêutico , Polipropilenos/uso terapêutico , Telas Cirúrgicas , Abdominoplastia/métodos , Animais , Modelos Animais de Doenças , Elasticidade , Hérnia Abdominal/etiologia , Hérnia Abdominal/cirurgia , Herniorrafia/métodos , Hérnia Incisional/etiologia , Hérnia Incisional/cirurgia , Teste de Materiais , Coelhos , Resistência à TraçãoRESUMO
The breakdown of intestinal anastomosis is a serious postsurgical complication. The worst complication is anastomotic leakage, resulting in contaminated peritoneal cavity, sepsis, multi-organ failure and even death. In problematic locations like the rectum, the leakage rate has not yet fallen below 10 %. Such a life-threatening condition is the result of impaired healing in the anastomotic wound. It is still vital to find innovative strategies and techniques in order to support regeneration of the anastomotic wound. This paper reviews the surgical techniques and biomaterials used, tested or published. Electrospun nanofibers are introduced as a novel and potential material in gastrointestinal surgery. Nanofibers possess several, unique, physical and chemical properties, that may effectively stimulate cell proliferation and collagen production; a key requirement for the healed intestinal wound.
Assuntos
Anastomose Cirúrgica , Intestinos/cirurgia , Nanofibras/uso terapêutico , Regeneração , Fístula Anastomótica/prevenção & controle , Animais , Materiais Biocompatíveis , HumanosRESUMO
The biofunctionalization of scaffolds for tissue engineering is crucial to improve the results of regenerative therapies. This study compared the effect of platelet-functionalization of 2D electrospun and 3D centrifugal spun scaffolds on the osteogenic potential of hMSCs. Scaffolds prepared from poly-ε-caprolactone, using electrospinning and centrifugal spinning technology, were functionalized using five different concentrations of platelets. Cell proliferation, metabolic activity and osteogenic differentiation were tested using hMSCs cultured in differential and non-differential medium. The porous 3D structure of the centrifugal spun fibers resulted in higher cell proliferation. Furthermore, the functionalization of the scaffolds with platelets resulted in a dose-dependent increase in cell metabolic activity, proliferation and production of an osteogenic marker - alkaline phosphatase. The effect was further promoted by culture in an osteogenic differential medium. The increase in combination of both platelets and osteogenic media shows an improved osteoinduction by platelets in environments rich in inorganic phosphate and ascorbate. Nevertheless, the results of the study showed that the optimal concentration of platelets for induction of hMSC osteogenesis is in the range of 900-3000â¯×â¯109â¯platelets/L. The study determines the potential of electrospun and centrifugal spun fibers with adhered platelets, for use in bone tissue engineering.
Assuntos
Plaquetas/metabolismo , Poliésteres/química , Engenharia Tecidual , Alicerces Teciduais/química , Fosfatase Alcalina/metabolismo , Plaquetas/citologia , Adesão Celular , Técnicas de Cultura de Células , Diferenciação Celular , Proliferação de Células , Módulo de Elasticidade , Humanos , Células-Tronco Mesenquimais/citologia , Células-Tronco Mesenquimais/metabolismo , Osteogênese , PorosidadeRESUMO
The aim of the study was to evaluate the safety and efficacy of a new therapeutic approach to skin defects resulting from split thickness grafting. Within the study, nanofiber-based dressings fabricated using polyvinyl alcohol (PVA) and poly-ε-caprolactone (PCL) were used, with different mass density. The study was performed in 1 female minipig. Nine defects (approx. 4x4 cm) were made in the superficial skin layer. The tested materials were applied to the squared skin defect and covered by a Jelonet paraffin gauze, sutured in the corners of the defects. The animal was monitored daily during the healing process (21 days). On day 5, 12, and 27, the healing of the wound was evaluated, and a biopsy was performed for further histologic testing. At the end of the study (on day 27 after the procedure), the animal was euthanized, and a standard pathologic evaluation was performed. We can conclude that the nanofiber scaffold which was well tolerated, could be used as a smart skin cover which could be functionalized with another bioactive substances directly on the surgeon table, among potential bioactive substances belong platelet derivatives, antibiotics, etc.
Assuntos
Bandagens , Nanofibras/uso terapêutico , Cicatrização , Animais , Poliésteres , Álcool de Polivinil , Suínos , Porco MiniaturaRESUMO
Additive manufacturing, also called 3D printing, is an effective method for preparing scaffolds with defined structure and porosity. The disadvantage of the technique is the excessive smoothness of the printed fibers, which does not support cell adhesion. In the present study, a 3D printed scaffold was combined with electrospun classic or structured nanofibers to promote cell adhesion. Structured nanofibers were used to improve the infiltration of cells into the scaffold. Electrospun layers were connected to 3D printed fibers by gluing, thus enabling the fabrication of scaffolds with unlimited thickness. The composite 3D printed/nanofibrous scaffolds were seeded with primary chondrocytes and tested in vitro for cell adhesion, proliferation and differentiation. The experiment showed excellent cell infiltration, viability, and good cell proliferation. On the other hand, partial chondrocyte dedifferentiation was shown. Other materials supporting chondrogenic differentiation will be investigated in future studies.
Assuntos
Adesão Celular/fisiologia , Condrócitos/citologia , Nanofibras , Impressão Tridimensional , Alicerces Teciduais , Diferenciação Celular/fisiologia , Proliferação de Células/fisiologia , Células Cultivadas/fisiologia , Humanos , Nanofibras/química , Engenharia Tecidual/métodosRESUMO
Fibrous scaffolds are desired in tissue engineering applications for their ability to mimic extracellular matrix. In this study we compared fibrous scaffolds prepared from polycaprolactone using three different fabrication methods, electrospinning (ES), electro-blowing and melt-blown combined with ES. Scaffolds differed in morphology, fiber diameters and pore sizes. Mesenchymal stem cell adhesion, proliferation and osteogenic differentiation on scaffolds was evaluated. The most promising scaffold was shown to be melt-blown in combination with ES which combined properties of both technologies. Microfibers enabled good cell infiltration and nanofibers enhanced cell adhesion. This scaffold was used for further testing in critical sized defects in rabbits. New bone tissue formation occurred from the side of the treated defects, compared to a control group where only fat tissue was present. Polycaprolactone fibrous scaffold prepared using a combination of melt-blown and ES technology seems to be promising for bone regeneration. The practical application of results is connected with enormous production capacity and low cost of materials produced by melt-blown technology, compared to other bone scaffold fabrication methods.
Assuntos
Osso e Ossos/patologia , Nanofibras/química , Osteogênese/efeitos dos fármacos , Engenharia Tecidual/métodos , Alicerces Teciduais/química , Animais , Regeneração Óssea , Adesão Celular , Proliferação de Células , Sobrevivência Celular , Fêmur/patologia , Masculino , Células-Tronco Mesenquimais/citologia , Microscopia Eletrônica de Varredura , Polímeros/química , CoelhosRESUMO
Restraint-based comparative modeling was used for calculation and visualization of the H4-H5-loop of Na+/K+-ATPase from mouse brain (Mus musculus, adult male brain, alpha2-isoform) between the amino acid residues Cys 336 and Arg 758 in the E1 conformation The structure consists of two well separated parts. The N-domain is formed by a seven-stranded antiparallel beta-sheet with two additional beta-strands and five alpha-helices sandwiching it, the P-domain is composed of a typical Rossman fold. The ATP-binding site was found on the N-domain to be identical in both alpha2- and alpha1-isoforms. The phosphorylation Asp 369 residue was found in the central part of the P-domain, located at the C-terminal end of the central beta-sheet. The distance between the alpha-carbon of Phe 475 at the ATP-binding site and the alpha-carbon of Asp 369 at the phosphorylation site is 3.22 nm. A hydrogen bond between the oxygen atom of Asp 369 and the nitrogen atom of Lys 690 was clearly detected and assumed to play a key role in maintaining the proper structure of the phosphorylaton site in E1 conformation.
Assuntos
Encéfalo/enzimologia , Modelos Moleculares , ATPase Trocadora de Sódio-Potássio/química , Trifosfato de Adenosina/metabolismo , Sequência de Aminoácidos , Animais , Sítios de Ligação , Gráficos por Computador , Ligação de Hidrogênio , Imageamento Tridimensional , Isoenzimas/química , Masculino , Camundongos , Dados de Sequência Molecular , Fosforilação , Conformação Proteica , Estrutura Terciária de Proteína , Reprodutibilidade dos Testes , Alinhamento de Sequência , Homologia de Sequência de Aminoácidos , ATPase Trocadora de Sódio-Potássio/metabolismoRESUMO
Patients treated for knee disorders were included in this study. They were examined clinically (Lequesne and Tegner scores) and by standard X-ray investigation. Patients underwent a surgical procedure, either arthroscopy or knee replacement. At the initial phase of surgery, a sample of cartilage was taken for laboratory examination. Progression of the disorder and the clinical examination was correlated with the actual state of the cartilage using a novel fluorescence approach. The intrinsic fluorescence of cartilages was shown as a suitable and sensitive method for detection of the actual state of cartilages because the correlation with X-ray examination and clinical status was found. Intrinsic fluorescence properties of cartilages from patients with chondropathy and osteoarthritis were described and found to be age-dependent. We also observed a higher concentration of advanced glycation end products due to inflammatory and/or degenerative processes in the cartilage. In addition, acute pathological changes due to diseases such as meniscal lesions or anterior cruciate ligament rupture caused a significant increase of formation of advanced glycation end products even in the group of young patients. In fact, such an observation could be crucial and important for the detection of knee conditions suspected of early meniscal and/or ACL lesions especially among young patients.
Assuntos
Doenças das Cartilagens/diagnóstico , Cartilagem Articular/metabolismo , Produtos Finais de Glicação Avançada/metabolismo , Artropatias/diagnóstico , Traumatismos do Joelho/diagnóstico , Articulação do Joelho/metabolismo , Espectrometria de Fluorescência , Adolescente , Adulto , Distribuição por Idade , Fatores Etários , Idoso , Idoso de 80 Anos ou mais , Artroplastia do Joelho , Artroscopia , Doenças das Cartilagens/diagnóstico por imagem , Doenças das Cartilagens/metabolismo , Doenças das Cartilagens/cirurgia , Cartilagem Articular/diagnóstico por imagem , Cartilagem Articular/cirurgia , Feminino , Humanos , Artropatias/diagnóstico por imagem , Artropatias/metabolismo , Artropatias/cirurgia , Traumatismos do Joelho/diagnóstico por imagem , Traumatismos do Joelho/metabolismo , Traumatismos do Joelho/cirurgia , Articulação do Joelho/diagnóstico por imagem , Articulação do Joelho/cirurgia , Masculino , Pessoa de Meia-Idade , Osteoartrite do Joelho/diagnóstico , Osteoartrite do Joelho/metabolismo , Valor Preditivo dos Testes , Radiografia , Sensibilidade e Especificidade , Índice de Gravidade de Doença , Sinovite/diagnóstico , Sinovite/metabolismoRESUMO
ECM is composed of different collagenous and non-collagenous proteins. Collagen nanofibers play a dominant role in maintaining the biological and structural integrity of various tissues and organs, including bone, skin, tendon, blood vessels, and cartilage. Artificial collagen nanofibers are increasingly significant in numerous tissue engineering applications and seem to be ideal scaffolds for cell growth and proliferation. The modern tissue engineering task is to develop three-dimensional scaffolds of appropriate biological and biomechanical properties, at the same time mimicking the natural extracellular matrix and promoting tissue regeneration. Furthermore, it should be biodegradable, bioresorbable and non-inflammatory, should provide sufficient nutrient supply and have appropriate viscoelasticity and strength. Attributed to collagen features mentioned above, collagen fibers represent an obvious appropriate material for tissue engineering scaffolds. The aim of this minireview is, besides encapsulation of the basic biochemical and biophysical properties of collagen, to summarize the most promising modern methods and technologies for production of collagen nanofibers and scaffolds for artificial tissue development.
Assuntos
Colágeno/química , Matriz Extracelular/química , Nanoestruturas , Engenharia Tecidual , Alicerces Teciduais , Animais , Citoesqueleto/química , Elasticidade , Proteínas da Matriz Extracelular/química , Humanos , Teste de Materiais , Estresse Mecânico , ViscosidadeRESUMO
Mechanical properties of scaffolds seeded with mesenchymal stem cells used for cartilage repair seem to be one of the critical factors in possible joint resurfacing. In this paper, the effect of adding hyaluronic acid, hydroxyapatite nanoparticles or chitosan nanofibers into the cross-linked collagen I on the mechanical response of the lyophilized porous scaffold has been investigated in the dry state at 37 oC under tensile loading. Statistical significance of the results was evaluated using ANOVA analysis. The results showed that the addition of hyaluronic acid significantly (p<<0.05) reduced the tensile elastic modulus and enhanced the strength and deformation to failure of the modified cross-linked collagen I under the used test conditions. On the other hand, addition of hydroxyapatite nanoparticles and chitosan nanofibers, respectively, increased the elastic modulus of the modified collagen ten-fold and four-fold, respectively. Hydroxyapatite caused significant reduction in the ultimate deformation at break while chitosan nanofibers enhanced the ultimate deformation under tensile loading substantially (p<<0.05). The ultimate tensile deformation was significantly (p<<0.05) increased by addition of the chitosan nanofibers. The enhanced elastic modulus of the scaffold was translated into enhanced resistance of the porous scaffolds against mechanical load compared to scaffolds based on cross-linked neat collagen or collagen with hyaluronic acid with similar porosity. It can be concluded that enhancing the rigidity of the compact scaffold material by adding rigid chitosan nanofibers can improve the resistance of the porous scaffolds against compressive loading, which can provide more structural protection to the seeded mesenchymal stem cells when the construct is implanted into a lesion. Moreover, scaffolds with chitosan nanofibers seemed to enhance cell growth compared to the neat collagen I when tested in vitro as well as the scaffold stability, extending its resorption to more than 10 weeks.
Assuntos
Materiais Biocompatíveis , Cartilagem , Quitosana/química , Colágeno Tipo I/química , Durapatita/química , Ácido Hialurônico/química , Engenharia Tecidual , Alicerces Teciduais , Animais , Bovinos , Proliferação de Células , Células Cultivadas , Elasticidade , Liofilização , Humanos , Teste de Materiais , Células-Tronco Mesenquimais/metabolismo , Nanopartículas , Porosidade , Falha de Prótese , Resistência à TraçãoRESUMO
The effect of oral supplementation with glycosaminoglycans (GAG) and radical scavengers (vitamin E/selenium) on the regeneration of osteochondral defects was investigated in rabbits. After introduction of defined osteochondral defects in the knee joint, groups of ten animals were given a GAG/vitamin E/selenium mixture or a placebo (milk sugar) for 6 weeks. Following sacrifice, histological and histochemical analysis was performed. The amount of synovial fluid was increased in the placebo group, while the viscosity of the synovial fluid was significantly enhanced in the GAG group. The amount of sulfated GAG in the osteochondral regenerates (8.8 +/- 3.6 % vs. 6.0 +/- 5.6 %; p <0.03) was significantly higher in the GAG group. In both groups, the GAG amount in the cartilage of the operated knee was significantly higher than in the non-involved knee (p <0.05). Histological analysis of the regenerates in the GAG group was superior in comparison with the placebo group. For the first time, a biological effect following oral supplementation with GAG was demonstrated in healing of osteochondral defects in vivo. These findings support the known positive clinical results.
Assuntos
Antioxidantes/farmacologia , Cartilagem Articular/efeitos dos fármacos , Glicosaminoglicanos/farmacologia , Articulação do Joelho/efeitos dos fármacos , Osteocondrite/tratamento farmacológico , Regeneração/efeitos dos fármacos , Administração Oral , Animais , Antioxidantes/administração & dosagem , Antioxidantes/uso terapêutico , Cartilagem Articular/metabolismo , Cartilagem Articular/patologia , Cartilagem Articular/fisiopatologia , Modelos Animais de Doenças , Combinação de Medicamentos , Feminino , Glicosaminoglicanos/administração & dosagem , Glicosaminoglicanos/metabolismo , Glicosaminoglicanos/uso terapêutico , Articulação do Joelho/metabolismo , Articulação do Joelho/patologia , Articulação do Joelho/fisiopatologia , Osteocondrite/metabolismo , Osteocondrite/patologia , Osteocondrite/fisiopatologia , Coelhos , Selênio/farmacologia , Líquido Sinovial/química , Líquido Sinovial/efeitos dos fármacos , Resultado do Tratamento , Viscosidade , Vitamina E/farmacologiaRESUMO
Computed tomography (CT) is an effective diagnostic modality for three-dimensional imaging of bone structures, including the geometry of their defects. The aim of the study was to create and optimize 3D geometrical and real plastic models of the distal femoral component of the knee with joint surface defects. Input data included CT images of stifle joints in twenty miniature pigs with iatrogenic osteochondrosis-like lesions in medial femoral condyle of the left knee. The animals were examined eight and sixteen weeks after surgery. Philips MX 8000 MX and View workstation were used for scanning parallel plane cross section slices and Cartesian discrete volume creation. On the average, 100 slices were performed in each stifle joint. Slice matrices size was 512 x 512 with slice thickness of 1 mm. Pixel (voxel) size in the slice plane was 0.5 mm (with average accuracy of +/-0.5 mm and typical volume size 512 x 512 x 100 voxels). Three-dimensional processing of CT data and 3D geometrical modelling, using interactive computer graphic system MediTools formerly developed here, consisted of tissue segmentation (raster based method combination and 5 % of manual correction), vectorization by the marching-cubes method, smoothing and decimation. Stifle- joint CT images of three individuals of different body size (small, medium and large) were selected to make the real plastic models of their distal femurs from plaster composite using rapid prototyping technology of Zcorporation. Accuracy of the modeling was +/- 0.5 mm. The real plastic models of distal femurs can be used as a template for developing custom made press and fit scaffold implants seeded with mesenchymal stem cells that might be subsequently implanted into iatrogenic joint surface defects for articular cartilage-repair enhancement.