1,720,967 research outputs found
New strategies for tissue regeneration
Full text linkMy PhD project is divided in two parts, focusing on the development of new strategies for orthopedic tissue regeneration. In particular, the first part is about cartilage regeneration using human lipoaspirate as autologous injectable active scaffold for one-step repair of cartilage defects, the second part is about bone regeneration, through an injectable medicated graft substitute active on bone tissue regeneration.
I. Cartilage regeneration
Research on mesenchymal stem cells from adipose tissue (ASC) shows promising results for cell-based therapy in cartilage lesions: in these studies cells have been isolated, expanded, and differentiated in vitro, before transplantation into the damaged cartilage, or onto materials used as scaffolds to deliver cells to the impaired area. The present study employed in vitro assays to investigate the potential of intra-articular injection of micro-fragmented lipoaspirate, as a one-step repair strategy; it aimed to determine whether adipose tissue can act as a scaffold for cells naturally present at their anatomical site. Cultured clusters of lipoaspirate showed a spontaneous outgrowth of cells with mesenchymal phenotype and with multilineage differentiation potential. Transduction of lipoaspirate clusters by lentiviral vectors expressing GFP underlined the propensity of the outgrown cells to repopulate fragments of damaged cartilage. On the basis of the results, which showed an induction of proliferation and extracellular matrix (ECM) production of human primary chondrocytes, it was hypothesized that lipoaspirate may play a paracrine role. Moreover, the structure of a floating culture of lipoaspirate, treated for three weeks with chondrogenic growth factors, changed: tissue with a high fat component was replaced by a tissue with a lower fat component and connective tissue rich in glycosaminoglycan (GAG) and in collagen type I, increasing the mechanical strength of the tissue. From these promising in vitro results, it may be speculated that an injectable autologous biologically-active scaffold (lipoaspirate), employed intra-articularly, may: 1) become a fibrous tissue that provides mechanical support for the load on the damaged cartilage; 2) induce host chondrocytes to proliferate and produce ECM; 3) provide cells at the site of injury, which could regenerate or repair the damaged or missing cartilage.
II. Bone regeneration
With the aim to obtain an injectable medicated scaffold, which speeds bone formation in sinus lift augmentation, in bony void and in fracture repair, we have developed a three-dimensional (3D) jelly collagen containing Lysophosphatidic acid (LPA) and 1a,25-Dihydroxyvitamin D3 (1,25D3) using soluble native collagen prepared from rat tail tendons. We have demonstrated with an in vitro 3D culture model of bone fracture an osteoblasts’Rho-kinase mediated contraction of the collagen that causes an approach of human bone trabecular fragments with the formation of new union tissue within 3 weeks of organ culture. The contraction was faster in LPA medicated collagen while 1,25D3 enhanced the mineralization of the new formed tissue that showed also increased tensile strength. LPA was shown to modulate gel contraction rate not only mechanically, working in cytoskeleton reorganization, but also osteoconductively evidencing activity on proliferation, differentiation and migration of human primary osteoblasts (hOB). When LPA was used in combination with 1,25D3 a synergism on hOB’s activity in term of alkaline phosphatase and mineralization was seen. On the basis of these data, collagen can be considered as an injectable natural scaffold that allows the migration of cells from the side of bone defect and its enrichment with LPA and 1,25D3 could be used in vivo to accelerate bone growth and fracture healing
Can human lipoaspirate be considered an autologous injectable scaffold to repair cartilage defects?
No full text
Injectable bone-graft substitute for in vivo tissue regeneration
Full text linkWe have demonstrated that using growth factors we can induce the proliferation of human primary osteoblasts but it isn’t enough to form new bone that need also the differentiation of the proliferated osteoblasts [1]. Being these two steps regulated by different pathways and different stimuli, in the same work we have found the combination of a proliferating growth factor (FGF2) with a differentiating stimulus (1,25Vit D3) as an optimal solution. With the aim to develop an injectable medicated scaffold which speeds bone formation in sinus lift augmentation, in bony void and in fracture repair, we have tested in vitro osteoblasts’ behavior in a 3D jelly collagen model (1mg/ml) using soluble native collagen prepared from rat tail tendons [2]. We have seen an osteoblasts’ Rho-kinase mediated contraction of the collagen that causes an approach of bone fragments within a week of culture with the formation of a fibrous bone tissue within 3 weeks of culture. FGF2 addition to the collagen fastened this result by increasing cell proliferation rate while the addition of 1,25Vit D3 to collagen at a concentration of 0,1 mg/mL that shows at HPLC analysis a release of 0,26 mcg/ ml/day during the incubation time studied, favors the mineralization of the new formed tissue that shows also increased tensile strenght. We think that this combination of factors could be used in vivo to accelerate bone growth and fracture healing
Human lipoaspirate as autologous injectable active scaffold for one-step repair of cartilage defects
Full text linkResearch on mesenchymal stem cells from adipose tissue shows promising results for cell-based therapy in cartilage lesions. In these studies, cells have been isolated, expanded, and differentiated in vitro before transplantation into the damaged cartilage or onto materials used as scaffolds to deliver cells to the impaired area. The present study employed in vitro assays to investigate the potential of intra-articular injection of microfragmented lipoaspirate as a one-step repair strategy; it aimed to determine whether adipose tissue can act as a scaffold for cells naturally present at their anatomical site. Cultured clusters of lipoaspirate showed a spontaneous outgrowth of cells with a mesenchymal phenotype and with multilineage differentiation potential. Transduction of lipoaspirate clusters by lentiviral vectors expressing GFP evidenced the propensity of the outgrown cells to repopulate fragments of damaged cartilage. On the basis of the results, which showed
an induction of proliferation and ECM production of human primary chondrocytes, it was hypothesized that lipoaspirate may play a paracrine role. Moreover, the structure of a floating culture of lipoaspirate, treated for 3 weeks with chondrogenic growth factors, changed: tissue with a high fat component was replaced by a tissue with a lower fat component and connective tissue rich in GAG and in collagen type I, increasing the mechanical strength of the tissue. From these promising in vitro results, it may be speculated that an injectable autologous biologically active scaffold (lipoaspirate), employed intra-articularly, may 1) become a fibrous tissue that provides mechanical support for the load on the damaged cartilage; 2) induce host chondrocytes to proliferate and produce ECM; and 3) provide cells at the site of injury, which could regenerate or repair the damaged or missing cartilage
Chondral tissue engineering of the reumatoid knee with collagen matrix autologous chondrocytes implant
No full textArticular cartilage repair is still a challenge. To date evidence is insufficient to support a treatment over the others. Inflammatory conditions in the joint hamper the application of tissue engineering during chronic joint diseases. Most of the Matrix Autologous Chondrocyte Implantation (MACI) cases reported in literature do not deal with rheumatoid knees and do not have a long clinical-histologic follow-up. We report about a 46-year old woman who suffered of a painful focal Outerbridge 4th degree chondral lesion in the medial femoral condyle of her left rheumatoid knee. The tissue defect was filled by a Cartilage Regeneration System (CaReS®) based on a type I collagen matrix seeded by autologous in vitro expanded chondrocytes. The patient was followed up to ten years clinically and by MRI, and finally treated with a Total Knee Replacement for the increasing arthritis. Histologically, the explanted MACI tissue showed an increased cellularity with an extracellular matrix rich of collagen and glycosaminoglicanes even though the overall architecture was different from the normal cartilage pattern. The case reported suggests that the main goal of treatment for chondropathy is the long lasting control of symptoms, while permanent restoration of normal anatomy is still impossible. Mesenchymal stem cells, that develop into joint tissues, show immunosuppressive and antiinflammatory qualities, in vitro and in vivo, indicating a potential role for tissue engineering approaches in the treatment of rheumatic diseases
A study of the mechanical properties of ePTFE suture used as artificial mitral chordae
No full textBackground and aim of the study: We investigated the dimensional and mechanical properties of polyetetrafluorene (ePTFE) sutures used as artificial chordae during mitral valve repair. Methods: Mechanical properties of ePTFE synthetic chordae tendineae were tested with a servo hydraulic testing machine. Several different lengths from 2 to 14 cm were studied under both single and multiple mechanical traction. Results: The mechanical behavior of artificial chordae reveals that three centimeters is the length over which we observe a significant increase in stiffness. The chordae stiffness grows further at the length greater than seven centimeters following a low number of traction cycles. Conclusion: The increase of the length of artificial ePTFE chordae is accompanied by an increasing stiffness that compromises the long-term resistance of the chordae. ePTFE length can alter the performance of artificial chordae. This suggests that mitral valve repairs which anchor ePTFE neochordae to the ventricular apex may have less durability than when anchored to the tips of the papillary muscles. © 2016 Wiley Periodicals, Inc
Injectable graft substitute active on bone tissue regeneration
No full textWith the aim to obtain an injectable bioactive scaffold that can accelerate bone formation in sinus lift augmentation, in bony void and in fracture repair, we have developed a three-dimensional (3D) jelly collagen containing Lysophosphatidic acid (LPA) and 1α,25-Dihydroxyvitamin D3 (1,25D3). Using an in vitro 3D culture model of bone fracture we show that the contraction of the collagen gel is mediated by Rho-kinase activation in osteoblasts. This contraction was cell concentration dependent and was increased by LPA which favored apposition and fastening of bone fragments approach. LPA was shown to act through actin cytoskeleton reorganization and myosin light chain phosphorylation of human primary osteoblasts (hOB). Moreover LPA conferred osteoconductive properties as evidenced by the induction of proliferation, differentiation and migration of hOB. The addition of 1,25D3 did not enhance cell mediated gel contraction but stimulated the maturation of hOB in vitro through the production of extra cellular matrix of higher quality. On the basis of these observations, the collagen gel enriched with LPA and 1,25D3 described herein can be considered as an injectable natural scaffold that allows the migration of cells from the side of bone defect and as a promising candidate to accelerate bone growth and fracture healing
- …
