Bio-Medical Materials and Engineering - Volume 18, issue s1
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Bio-Medical Materials and Engineering is to promote the welfare of humans and to help them keep healthy. This international journal is an interdisciplinary journal that publishes original research papers, review articles and brief notes on materials and engineering for biological and medical systems.
Articles in this peer-reviewed journal cover a wide range of topics, including, but not limited to: Engineering as applied to improving diagnosis, therapy, and prevention of disease and injury, and better substitutes for damaged or disabled human organs; Studies of biomaterial interactions with the human body, bio-compatibility, interfacial and interaction problems; Biomechanical behavior under biological and/or medical conditions; Mechanical and biological properties of membrane biomaterials; Cellular and tissue engineering, physiological, biophysical, biochemical bioengineering aspects; Implant failure fields and degradation of implants. Biomimetics engineering and materials including system analysis as supporter for aged people and as rehabilitation; Bioengineering and materials technology as applied to the decontamination against environmental problems; Biosensors, bioreactors, bioprocess instrumentation and control system; Application to food engineering; Standardization problems on biomaterials and related products; Assessment of reliability and safety of biomedical materials and man-machine systems; and Product liability of biomaterials and related products.
Abstract: Mesenchymal Stem Cells (MSCs) are multipotent adult stem cells having an immunosuppressive effect. These characteristics lead to an increasing use of MSC in graft process or for regenerative medicine. For the clinical uses of MSCs, standards are needed. The clinical grade production necessitates adhering to good manufacturing practices (GMP) to insure the delivery of a “cell drug” that is safe, reproducible and efficient. All parts of the process must be defined: the starting material (tissue origin, separation or enrichment procedures), cell density in culture, and medium (fetal calf serum (FCS) or human serum, cytokines with serum-free medium for target).…But to reach the GMP goal, cells have to be cultured in as close to a closed system as possible. Analytical methods are needed to assay the active compound and impurities. At a minimum, quality control (QC) of cells must consider the phenotype, functional potential, microbiological safety, and ensure the cultured cells remain untransformed. Finally, quality assurance system (QA) procedures specific to the production of MSCs as a cell drug must be determined and implemented.
Abstract: Cell therapies are unique in that the active component consists of living cells, which are difficult to define in their pharmacologic characteristics, and which produce variable and largely unknown amounts of bioactive molecules. Thus, the definition of the composition of a cellular product, mechanisms of action, pharmacokinetics, toxicity and efficacy assessment represent challenges never previously faced by traditional pharmacology. A pressing need for a routine use of cell therapies in the clinic is the development of quality controls for efficacy on the basis of clinically relevant potency assays, with prospective validation in human clinical trials. This review will focus on…cell-based protocols for joint surface repair. In particular, we will present the case of autologous chondrocyte implantation as an example of advanced tissue engineering technology in the clinic, with the assumption that many issues discussed can be extrapolated to other cell-based approaches in regenerative medicine.
Abstract: Chimerism analysis has become an important tool to manage patients in the peri-transplant period of allogenic stem cell transplantation. During this period, cells of donor and host origin can coexist and increasing proportion of cells of host origin is considered as a recurrence of the underlying disease. We currently performed chimerism analysis on separate peripheral blood cell subsets, lymphocytes and granulocytes. To improve our isolation method, a new automated device from Stem Cell Technology Robosep™ was tested and compared to our manual separation technique. The results obtained on T cell purification showed an improvement of the purity (98.42% with…Robosep vs. 92.42% with the manual technique Rosettesep) and of the recovery (63.43% with Robosep and 38% with Rosettesep). The results were significantly improved on patient samples with less than 10% CD3 positive cells (purity: 90% vs. 44.44%; recovery: 73.79% vs. 43.98%). Granulocytes separation was based on CD15 expression. The results showed an improvement of the purity with Robosep (96.90% vs. 86.20% with the manual technique Polymorphprep) but the recovery was impaired (35.2% vs. 52.30%). Using a myeloid (CD66/CD33) cocktail, recovery was improved with the Robosep device (64.04% with the myeloid cocktail vs. 22.4% with the CD15 cocktail). Our data demonstrated that Robosep allowed a performant cell purification in the early period post-transplantation even for populations representing less than 10% of the peripheral blood cells.
Abstract: Intracoronary infusion of autologous bone marrow cells (CTX) has been shown to improve myocardial function in post infarct patients and in patients with chronic ischemic cardiomyopathy. Whether CTX affects exercise-induced changes in cardiac deformation and mitral regurgitation (MR) in patients with end stage heart failure has not been studied. In this small pilot study, eleven patients with chronic ischemic cardiomyopathy, ejection fraction (EF) <25%, no inducible ischemia and heart failure class NYHA III underwent CTX. Symptom-limited bicycle exercise echocardiography was performed pre- and 4 months post CTX and maximum systolic strain (msyε), peak systolic strain rate (psysr) and effective…regurgitant orifice of MR (ERO) were determined. There were no complications related to the procedure. The overall clinical benefit of CTX was limited with a trend towards improvement (NYHA 3.0±0.1 pre and 2.7±0.2 post CTX, p=0.06). The EF did not improve after CTX. The wall motion score index (WMSI) did not change at rest but decreased significantly during exercise (1.48±0.16 vs. 1.44±0.17, p=0.01). In conclusion, CTX may improve cardiac deformation and MR during exercise in patients with severe chronic heart failure when viable areas are targeted.
Keywords: Cell therapy, heart failure, stress echocardiography, bone marrow cells
Abstract: Articular cartilage has a limited capacity for self-repair after trauma. Besides the conventional surgical techniques for repairing such defects, treatments involve implantation of autologous cells in suspension or within a variety of cell carrying scaffolds such as hyaluronic acid, alginate, agarose/alginate, fibrin or collagen. For the repair of full-thickness osteochondral defects, tissue engineers started to design single- or bi-phased scaffold constructs often containing hydroxyapatite-collagen composites, usually used as a bone substitute. The purpose of this study was to compare the behavior of bovine chondrocytes cultured in collagen-based scaffolds containing or not hydroxyapatite and cross-linked following two different methods. Calf chondrocytes…seeded within Hemotèse® and Collapat® II sponges (SYMATESE biomaterials), chemically cross-linked with glutaraldehyde or EDC/NHS, were maintained up to one month in culture. The cells exhibited a similar behavior in the four scaffolds regarding proliferation level, deposition of glycosaminoglycans in the scaffolds and gene expression of types I, II and X collagens, aggrecan, MMP-1, -13 and the integrin subunits α10 and α11.
Abstract: To investigate whether the application of alginate culture and mechanical stimulation will improve the synthesis of cartilaginous matrix in dedifferentiated chondrocytes, rat chondrocytes underwent dedifferentiation upon serial monolayer culture up to passage 6, and then were encapsulated in 2% alginate gel and subject to static culture. After 28 days culture in static, the beads were exposed to 48 h of mechanical stimulation with continuous agitation. The sGAG content in alginate bead was measured by alcian blue staining. The expression of collagen protein was detected using immunofluorescence. After 28 days culture in alginate bead, the dedifferentiated chondrocytes remained round in shape…and re-synthesized the chondrocyte-specific matrix. Compared with static culture, mechanical stimulation induced statistically increases in the production of glycosaminoglycan (p≤0.01), as well as in the synthesis of collagen type II protein (p≤0.05). On the contrary, no positive expression of collagen type I protein was observed at the end of culture. Our results demonstrated that both of alginate culture and mechanical stimulation help to restore chondrocyte phenotype and promotes the synthesis of cartilaginous matrix.
Abstract: In this study we compared the in vitro formation of cartilaginous grafts composed of collagen type I hydrogel with both ovine primary articular chondrocytes (AC) and bone marrow derived mesenchymal stem cells (MSC). During 4 weeks of culture, aggregate properties were quantitatively verified, cell viability and the expression of cartilage markers were assayed. Different microscopic techniques indicated a subdivision of MSC based scaffolds into a central construct region with uniformly distributed stem cells with low levels of apoptosis, and peripheral layers of proliferative cells, which undergo differentiation. Immunohistochemical staining and quantitative measurements of sulfated glycosaminoglycans (s-GAG) of MSC hydrogels showed…a significant increase in matrix deposition, mainly in outer areas. Furthermore, semi-quantitative RT-PCR of MSC specimens reflected a constant collagen type I activity with enhanced collagen type II, aggrecan and Sox9 expression which would suggest hyaline-like cartilage formation. We propose the application of MSC seeded grafts for the repair of focal cartilage lesions.
Abstract: Mesenchymal stromal cells (MSC) are currently in focus because of their clinical potential in cell therapy and tissue engineering. As yet bone marrow represents the main source of MSC for both experimental and clinical studies. However, it is speculated that the clinical value might be diminished as both the number of MSC and their differentiation capacity decline with age. Alternatively, MSC have been successfully isolated from nearly every tissue attempted so far. Our work is focused on comparing MSC derived from human adult bone marrow, lipoaspirate as well as cord blood in terms of being alternatives containing high precursor frequencies…and youngest adult cells. Applying identical culture conditions, major differences were observable in the frequencies and expansion potential, whereas basic biological features were comparable. Since all three tissues have been shown to contain multipotential cells we consider aspects such as isolation efficacy, frequency and expansion potential may more likely affect MSC clinical exploitation.
Abstract: Tissue engineering requires the response of the cells to different stimuli inducing the synthesis of the extracellular matrix (ECM). It was been shown that mechanical and biochemical stimuli acted on the synthesis of ECM, particularly type I and III collagens. Growth factors implied in transduction pathways are multiple, but the main is TGF-β. Member of the transforming growth factor-β (TGF-β) family bind to type II and type I serine/threonine kinase receptors, which initiate intracellular signals through activation of SMADs proteins. Nevertheless, the effects of mechanical stress of this pathway remain unknown. The aim of this work was to study…the pathway of TGF-β via the SMADs proteins under mechanical (stretching) and biochemical (TGF-β) stimulations. Endogenous SMADs expression and its modulation by biochemical and mechanical stimulations were evaluated by both flow cytometry and confocal microscopy. Our results demonstrate that 10 ng of TGF-β and stretching (5%, 1 Hz) applied during 15 min induced a negative feed back loop which blocks the signalling pathway to control TGF-β activity. This inhibition effect was raised after 1 h of stimulation. Nevertheless, these preliminary studies should be continued by study of expression and localization of inhibitory SMADs (SMAD7).
Keywords: Signal transduction, TGF-β, SMAD proteins, stretching stimulation, fibroblasts