|  |  |  | | | | | TE-RegenMed-StemCell feed | | | | | | | | | | | | | | | | | | The California stem cell agency was admonished in December by the state's top fiscal officer concerning its performance in attempting to elect a new chair to head the $3 billion enterprise.
More transparency and openness are needed, said State Controller John Chiang, chair of the only state panel specifically charged with overseeing CIRM finances.
That advice is going unheeded this week. With | | | | | | | | | | | | | | | | | | | | | | | | | Stem cells therapy for retinal degeneration. Pak J Biol Sci. 2010 Nov 1;13(21):1016-22 Authors: Safari M Stem cell therapy is widely considered as a therapeutic approach for retinal degeneration. Retinal injury results in permanent visual disturbance or blindness. Repair of such damage by stem cells is one of the most feasible types of central nervous system repair. In this review, we consider how stem cells might be optimized for use as donor cells. We discuss the benefits of stem cells for transplantation in retinal degenerative disease. A wide range of stem cells from different sources is being investigated for the treatment of retinal degeneration. This study reviews the recent and old achievements about stem cells for retinal repair. PMID: 21313871 [PubMed - in process] | | | | | | | | | | | | | | | | | | | | | | | | | Hybrid adipogenic implants from adipose stem cells for soft tissue reconstruction in vivo. Tissue Eng Part A. 2010 Nov;16(11):3299-307 Authors: Moioli EK, Chen M, Yang R, Shah B, Wu J, Mao JJ A critical barrier in tissue regeneration is scale-up. Bioengineered adipose tissue implants have been limited to ∼10 mm in diameter. Here, we devised a 40-mm hybrid implant with a cellular layer encapsulating an acellular core. Human adipose-derived stem cells (ASCs) were seeded in alginate. Poly(ethylene)glycol-diacrylate (PEGDA) was photopolymerized into 40-mm-diameter dome-shaped gel. Alginate-ASC suspension was painted onto PEGDA surface. Cultivation of hybrid constructs ex vivo in adipogenic medium for 28 days showed no delamination. Upon 4-week in vivo implantation in athymic rats, hybrid implants well integrated with host subcutaneous tissue and could only be surgically separated. Vascularized adipose tissue regenerated in the thin, painted alginate layer only if ASC-derived adipogenic cells were delivered. Contrastingly, abundant fibrous tissue filled ASC-free alginate layer encapsulating the acellular PEGDA core in control implants. Human-specific peroxisome proliferator-activated receptor-γ (PPAR-γ) was detected in human ASC-seeded implants. Interestingly, rat-specific PPAR-γ was absent in either human ASC-seeded or ASC-free implants. Glycerol content in ASC-delivered implants was significantly greater than that in ASC-free implants. Remarkably, rat-specific platelet/endothelial cell adhesion molecule (PECAM) was detected in both ASC-seeded and ASC-free implants, suggesting anastomosis of vasculature in bioengineered tissue with host blood vessels. Human nuclear staining revealed that a substantial number of adipocytes were of human origin, whereas endothelial cells of vascular wall were of chemaric human and nonhuman (rat host) origins. Together, hybrid implant appears to be a viable scale-up approach with volumetric retention attributable primarily to the acellular biomaterial core, and yet has a biologically viable cellular interface with the host. The present 40-mm soft tissue implant may serve as a biomaterial tissue expander for reconstruction of lumpectomy defects. PMID: 20528671 [PubMed - indexed for MEDLINE] | | | | | | | | | | | | | | | | | | | | | | | | | Osteogenic comparison of expanded and uncultured adipose stromal cells. Cytotherapy. 2010 Jul;12(4):554-62 Authors: Cheung WK, Working DM, Galuppo LD, Leach JK Adipose stromal cells (ASC) are a promising alternative to progenitor cells from other tissue compartments because of their multipotential and capacity to retrieve significantly more progenitor cells. Initial cell samples are heterogeneous, containing a collection of cells that may contribute to tissue repair, but the sample becomes more homogeneous with each passage. Therefore, we hypothesized that the osteogenic potential of culture-expanded ASC would differ from uncultured ASC. PMID: 20370353 [PubMed - indexed for MEDLINE] | | | | | | | | | | | | | | | | | | | | | | | | | In pursuit of the newt. IEEE Pulse. 2011 Jan-Feb;2(1):26-33 Authors: Campbell S It looks like a frog-but with a tail. Its legs are as long as its arms. Some live in water, and some are semiaquatic, returning to water to breed. But perhaps what's most noteworthy about the newt is its remarkable ability to bounce back from what would be catastrophic injuries to other creatures. Front leg munched off by a predator? Another leg will grow in its place. Eye poked out by a fast-moving branch? The newt can fix that too. Even more complicated organs are not beyond the regenerative capacities of the little newt: intestines, spinal cord, and even heart can be recovered. It's superhero material and, more close to home, it's a model that researchers in regenerative medicine are not beyond aspiring to. Dr. Cato Laurencin was heard earlier this year encouraging his colleagues at the Annual Society for Biomaterials Conference to bring out the inner newt in all of us. Newts may be phylogenetically much lower than humans, but in the areas of regenerative medicine and tissue engineering, advances in research have propelled us to the point that we might, in fact, aspire to newtness-before us lies the possibility and project of figuring out how we too might grow an entire limb or repair whole organs at the site of injury. PMID: 21317064 [PubMed - in process] | | | | | | | | | | | | | | | | | | | | | | | | | Methods for forming human microvascular tubes in vitro and measuring their macromolecular permeability. Methods Mol Biol. 2011;671:281-93 Authors: Price GM, Tien J This chapter describes a protocol for forming open endothelial tubes in vitro and quantifying their permeability to macromolecules. These tubes consist of confluent monolayers of human microvascular endothelial cells in perfused microfluidic collagen gels. The cylindrical geometry of the tubes mimics the shape of microvessels in vivo; it allows simultaneous and/or repeated measurements of permeability coefficients and detection of focal leaks. We have used these in vitro models to test the effects of agonists on microvascular permeability and are developing arrays of microvascular tubes to enable large-scale testing. PMID: 20967637 [PubMed - indexed for MEDLINE] | | | | | | | | | | | | | | | | | | | | | | | | | Diels-Alder Click Cross-Linked Hyaluronic Acid Hydrogels for Tissue Engineering. Biomacromolecules. 2011 Feb 11; Authors: Nimmo CM, Owen SC, Shoichet MS Hyaluronic acid (HA) is a naturally occurring polymer that holds considerable promise for tissue engineering applications. Current cross-linking chemistries often require a coupling agent, catalyst, or photoinitiator, which may be cytotoxic, or involve a multistep synthesis of functionalized-HA, increasing the complexity of the system. With the goal of designing a simpler one-step, aqueous-based cross-linking system, we synthesized HA hydrogels via Diels-Alder "click" chemistry. Furan-modified HA derivatives were synthesized and cross-linked via dimaleimide poly(ethylene glycol). By controlling the furan to maleimide molar ratio, both the mechanical and degradation properties of the resulting Diels-Alder cross-linked hydrogels can be tuned. Rheological and degradation studies demonstrate that the Diels-Alder click reaction is a suitable cross-linking method for HA. These HA cross-linked hydrogels were shown to be cytocompatible and may represent a promising material for soft tissue engineering. PMID: 21314111 [PubMed - as supplied by publisher] | | | | | | | | | | | | | | | | | | | | | | | | | 10(th) annual meeting of the Safety Pharmacology Society: an overview. Expert Opin Drug Saf. 2011 Feb 14; Authors: Cavero I The 10(th) annual meeting of the Safety Pharmacology (SP) Society covered numerous topics of educational and practical research interest. Biopolymers - the theme of the keynote address - were presented as essential components of medical devices, diagnostic tools, biosensors, human tissue engineering and pharmaceutical formulations for optimized drug delivery. Toxicology and SP investigators - the topic of the Distinguished Service Award Lecture - were encouraged to collaborate in the development of SP technologies and protocols applicable to toxicology studies. Pharmaceutical companies, originally organizations bearing all risks for developing their portfolios, are increasingly moving towards fully integrated networks which outsource core activities (including SP studies) to large contract research organizations. Future nonclinical data are now expected to be of such high quality and predictability power that they may obviate the need for certain expensive and time-consuming clinical investigations. In this context, SP is called upon to extend its risk assessment purview to areas which currently are not systematically covered, such as drug-induced QRS interval prolongation, negative emotions and feelings (e.g., depression), and minor chronic cardiovascular and metabolic changes (e.g., as produced by drugs for type 2 diabetes) which can be responsible for delayed morbidity and mortality. The recently approved ICH S9 guidance relaxes the traditional regulatory SP package in order to accelerate the clinical access to anticancer drugs for patients with advanced malignancies. The novel FDA 'Animal Rule' guidance proposes that for clinical candidates with well-understood toxicities, marketing approval may be granted exclusively on efficacy data generated in animal studies as human clinical investigations for these types of drugs are either unfeasible or unethical. In conclusion, the core messages of this meeting are that SP should consistently operate according to the 'fit-for-purpose' principle and gradually integrate new mechanism-oriented safety paradigms into the traditional ones for ensuring more effectively the safety of drugs for any population of patients in need. PMID: 21314442 [PubMed - as supplied by publisher] | | | | | | | | | | | | | | | | | | | | | | | | | Methods for the Identification, Characterization and Banking of Human DPSCs: Current Strategies and Perspectives. Stem Cell Rev. 2011 Feb 12; Authors: Tirino V, Paino F, d'Aquino R, Desiderio V, De Rosa A, Papaccio G Dental pulp stem cells (DPSCs), originating from neural crests, can be found within dental pulp. Up to now, it has been demonstrated that these cells are capable of producing bone tissue, both in vitro and in vivo and differentiate into adipocytes, endotheliocytes, melanocytes, neurons, glial cells, and can be easily cryopreserved and stored. Moreover, recent attention has been focused on tissue engineering and on the properties of these cells. In addition, adult bone tissue with good vascularisation has been obtained in grafts. The latest use in clinical trials for bone repair enforces the notion that DPSCs can be used successfully in patients. Therefore, their isolation, selection, differentiation and banking is of great importance. The isolation and detection techniques used in most laboratories are based on the use of antibodies revealed by flow-cytometers with cell sorter termed FACS (fluorescent activated cell sorter). In this report, we focus our attention on the main procedures used in the selection of DPSCs by flow cytometry, cell culture, freezing/thawing, cell cycle evaluation, histochemistry/immunofluorescence and differentiation of DPSCs. In addition, new methods/protocols to select and isolate stem cells without staining by fluorescent markers for implementation in biomedical/clinical laboratories are discuss. We emphasize that the new methods must address simplicity and short times of preparation and use of samples, complete sterility of cells, the potential disposable, low cost and complete maintenance of the viability and integrity of the cells with real-time response for subsequent applications in the biomedical/clinical/surgical fields. PMID: 21318597 [PubMed - as supplied by publisher] | | | | | | | | | | | | | | | | | | | | | | | | | The decellularized vascular allograft as an experimental platform for developing a biocompatible small-diameter graft conduit in a rat surgical model. Yonsei Med J. 2011 Mar 1;52(2):227-33 Authors: Hwang SJ, Kim SW, Choo SJ, Lee BW, Im IR, Yun HJ, Lee SK, Song H, Cho WC, Lee JW Purpose: The present study was aimed to assess the feasibility of using decellularized aortic allograft in a rat small animal surgical model for conducting small diameter vascular tissue engineering research. Materials and Methods: Decellularized aortic allografts were infra-renally implanted in 12 Sprague-Dawley (SD) adult rats. The conduits were harvested at 2 (n = 6) and 8 weeks (n = 6), and assessed by hematoxylin and eosin (H&E), van Gieson, Masson Trichrome staining, and immunohistochemistry for von Willebrand factor, CD 31(+), and actin. Results: Consistent, predictable, and reproducible results were produced by means of a standardized surgical procedure. All animals survived without major complications. Inflammatory immune reaction was minimal, and there was no evidence of aneurysmal degeneration or rupture of the decellularized vascular implants. However, the aortic wall appeared thinner and the elastic fibers in the medial layer showed decreased undulation compared to the normal aorta. There was also minimal cellular repopulation of the vascular media. The remodeling appeared progressive from 2 to 8 weeks with increased intimal thickening and accumulation of both collagen and cells staining for actin. Although the endothelial like cells appeared largely confluent at 8 weeks, they were not as concentrated in appearance as in the normal aorta. Conclusion: The results showed the present rat animal model using decellularized vascular allograft implants to be a potentially durable and effective experimental platform for conducting further research on small diameter vascular tissue engineering. PMID: 21319339 [PubMed - in process] | | | | | | | | | | | | | | | | | | | | | | | | | Drug-Carrier/Hydrogel Scaffold for Controlled Growth of Cells. Eur J Pharm Biopharm. 2011 Feb 10; Authors: Wei L, Lin J, Cai C, Fang Z, Fu W In this work, a novel functional drug-carrier/hydrogel scaffold was prepared to control the growth of cells for tissue engineering. The drug-carrier/hydrogel scaffold was constructed from a micelle/Ca-alginate microparticles (Alg-MPs)/poly(vinyl alcohol) (PVA) hydrogel composite. In such a system, paclitaxel (PTX) is encapsulated in the micelles formed by poly(L-glutamic acid)-b-poly(propylene oxide)-b-poly(L-glutamic acid) (GPG), while human vascular endothelial growth factor-165 (VEGF(165)) is loaded in the Alg-MPs. The designed function of this scaffold is to encourage the fast growth of cells such as endothelial cells (ECs) in the early period to reduce the rejection, and inhibit the growth of cells such as smooth muscle cells (SMCs) in late period to prevent the vascular intimal hyperplasia. The effect of VEGF(165) is to encourage the growth of ECs, while PTX is used to inhibit the growth of smooth muscle cells (SMCs). Structure characterizations show that the drug carriers are well dispersed in the PVA hydrogel. Independent release behaviors of the two drugs are observed. VEGF(165) shows a short-term release behavior while PTX shows a long-term release behavior from the drug-carrier/hydrogel scaffolds. Further study shows a controllable cell growth behavior on this functional drug-carrier/hydrogel scaffold via the MTT assay. PMID: 21316449 [PubMed - as supplied by publisher] | | | | | | | | | | | | | | | | | | | | | | | | | Nano/micro electro-spun polyethylene terephthalate fibrous mat preparation and characterization. J Mech Behav Biomed Mater. 2011 Apr;4(3):340-51 Authors: Hadjizadeh A, Ajji A, Bureau MN Electro-spun polyethylene terephthalate (PET) fibrous mats are potential substrates for biotechnological and biomedical applications. In this regard, substrate characteristics including, fiber diameter, orientation and mechanical properties play an important role in controlling the interaction of substrate with biological entities. However, few studies reporting the preparation of electro-spun PET substrates with such controlled characteristics have been published. In this study, electro-spun PET fibrous mats with fiber diameters in the nanometer and micrometer range were produced by varying polymer solution concentration and flow rate. Fiber orientation within the mats was also varied by varying collector surface velocities in rotation and translation. Their morphological, mechanical, thermal and structural properties were evaluated as a function of fiber diameter and collector speed using scanning electron microscopy (SEM), a micromechanical tester, differential scanning calorimetry (DSC) and X-ray diffraction (XRD), respectively. Varying polymer solution concentration and flow rate allowed the production of matrices with fiber diameters ranging from 400 nm to 2 μm. Tensile properties increased with fiber diameter and collector surface velocity. Thermal properties of electro-spun PET fibers were different from the structure of as received raw PET in the form of pellets, revealing an amorphous structure for the entire electro-spun PET. This was also confirmed by XRD analysis. No considerable differences were observed between electro-spun PET fibers, in terms of crystalline and thermal properties, produced under various conditions. These electro-spun mats with different fiber diameters, orientation and mechanical properties can be used for various applications including tissue engineering scaffolds. PMID: 21316622 [PubMed - in process] | | | | | | | | | | | | | | | | | | | | | | | | | In Vitro and In Vivo Degradation Profile of Aliphatic Polyesters Subjected to Electron Beam Sterilization. Acta Biomater. 2011 Feb 10; Authors: Dånmark S, Finne-Wistrand A, Schander K, Hakkarainen M, Arvidson K, Mustafa K, Albertsson AC Degradation characteristics in response to electron beam sterilization of designed and biodegradable aliphatic polyesters scaffolds are relevant for clinical successful synthetic graft tissue regeneration. Scaffold degradation in vitro and in vivo weredocumented and correlated to the macroscopic structure and chemical design of the original polymer. The materials tested were of inherently diverse hydrophobicity and crystallinity: poly(L-lactide) and random copolymers from L-lactide and ε-caprolactone or 1,5-dioxepan-2-one, fabricated into porous and non-porous scaffolds. After sterilization, the samples underwent hydrolysis in vitrofor up to a year. Invivo, scaffolds were surgically implanted into rat calvarial defects and retrieved for analysis after 28 and 91 days. In vitro, Poly(L-lactide-co-1,5-dioxepan-2-one) samples degraded most rapidly during hydrolysis, due to the pronounced chain-shortening reaction caused by the sterilization. Indicated by the rapidly decrease in mass and molecular weight of poly(LLA-co-DXO). Poly(L-Lactide-co-ε-caprolactone) samples were also strongly affected by sterilization, but mass loss was more gradual; molecular weight decreased rapidly during hydrolysis. Least affected by sterilization were the poly(L-lactide) samples, subsequently showing low mass loss rate and molecular weight decrease during hydrolysis. Mechanical stability varied greatly: poly(LLA-co-CL) withstood mechanical testing for up to 182 days, while poly(LLA) and poly(LLA-co-DXO) samples quickly became too brittle. Poly(LLA-co-DXO) samples unexpectedly degraded more rapidly in vivo than in vitro. After sterilization by electron beam irradiation, the three biodegradable polymers present widely diverse degradation profiles, both in vitro and in vivo. Each exhibits the potential to be tailored to meet diverse clinical tissue engineering requirements. PMID: 21316490 [PubMed - as supplied by publisher] | | | | | | | | | | | | | | | | | | | | | | | | | Heart valve tissue engineering: quo vadis? Curr Opin Biotechnol. 2011 Feb 9; Authors: Schoen FJ Surgical replacement of diseased heart valves by mechanical and tissue valve substitutes is now commonplace and generally enhances survival and quality of life. However, a fundamental problem inherent to the use of existing mechanical and biological prostheses in the pediatric population is their failure to grow, repair, and remodel. A tissue engineered heart valve could, in principle, accommodate these requirements, especially somatic growth. This review provides a brief overview of the field of heart valve tissue engineering, with emphasis on recent studies and evolving concepts, especially those that establish design criteria and key hurdles that must be surmounted before clinical implementation. PMID: 21315575 [PubMed - as supplied by publisher] | | | | | | | | | | | | | | | | | | | | | | | | | BMHP1-Derived Self-Assembling Peptides: Hierarchically Assembled Structures with Self-Healing Propensity and Potential for Tissue Engineering Applications. ACS Nano. 2011 Feb 11; Authors: Gelain F, Silva D, Caprini A, Taraballi F, Natalello A, Villa O, Nam KT, Zuckermann RN, Doglia SM, Vescovi A Self-assembling peptides (SAPs) are rapidly gaining interest as bioinspired scaffolds for cell culture and regenerative medicine applications. Bone Marrow Homing Peptide 1 (BMHP1) functional motif (PFSSTKT) was previously demonstrated to stimulate neural stem cell (NSC) viability and differentiation when linked to SAPs. We here describe a novel ensemble of SAPs, developed from the BMHP1 (BMHP1-SAPs), that spontaneously assemble into tabular fibers, twisted ribbons, tubes and hierarchical self-assembled sheets: organized structures in the nano- and microscale. Thirty-two sequences were designed and evaluated, including biotinylated and unbiotinylated sequences, as well as a hybrid peptide-peptoid sequence. Via X-ray diffraction (XRD), CD, and FTIR experiments we demonstrated that all of the BMHP1-SAPs share similarly organized secondary structures, that is, β-sheets and β-turns, despite their heterogeneous nanostructure morphology, scaffold stiffness, and effect over NSC differentiation and survival. Notably, we demonstrated the self-healing propensity of most of the tested BMHP1-SAPs, enlarging the set of potential applications of these novel SAPs. In in vitro cell culture experiments, we showed that some of these 10-mer peptides foster adhesion, differentiation, and proliferation of human NSCs. RGD-functionalized and hybrid peptide-peptoid self-assembling sequences also opened the door to BMHP1-SAP functionalization with further bioactive motifs, essential to tailor new scaffolds for specific applications. In in vivo experiments we verified a negligible reaction of the host nervous tissue to the injected and assembled BMHP1-SAP. This work will pave the way to the development of novel SAP sequences that may be useful for material science and regenerative medicine applications. PMID: 21314189 [PubMed - as supplied by publisher] | | | | | | | | | | | | | | | | | | | | | | | | | Osteoconductive properties of poly(96L/4D-lactide)/beta-tricalcium phosphate in long term animal model. Biomaterials. 2011 Feb 9; Authors: Daculsi G, Goyenvalle E, Cognet R, Aguado E, Suokas EO The objective of this study was to determine the effect of calcium phosphate mineral content on the bone in-growth at the expense of composite of co-polylactide polymer charged with 2 different ratios of β-TCP granules (10 and 24 w-% of β-TCP). The evaluation was realized in a long term rabbit bone model. After 24, 48 and 76 weeks, the implants were examined by micro CT, scanning electron microscopy (SEM) using backscattered electron (BSE) and light microscopy (polarized and blue light microscopy). No foreign body reaction was detected during the 76 weeks follow-up in any of the test samples. Polymer hydrolysis began at approximately 24 weeks, by 76 weeks, the pure polymer implant had begun to release P(96L/4D)LA particles and show signs of peripheral localized bone resorption. A decrease in the amount of CaP was noticed between 24 and 76 weeks in both 10 wt-% and 24 wt-% β-TCP/P(96L/4D)LA composites. The study showed that the highest bone in-growth was with 24 wt-% β-TCP/P(96L/4D)LA composite. Bone in-growth and mineralization were evident for the composites associated with specific peripheral bone architecture. Fluorescent labelling demonstrated high bone in-growth and remodeling at the interface, while for pure co-polymer no bone remodeling or bone activity was maintained after 48 weeks. The study demonstrated the positive effect of calcium phosphate content into P(96L/4D)LA. This kind of composite is a suitable resorbable osteoconductive matrix, which provides long term stability required for ligament fixation device. PMID: 21315446 [PubMed - as supplied by publisher] | | | | | | | | | | | | | | | | | | | | | | | | | Polymeric endoaortic paving: Mechanical, thermoforming, and degradation properties of polycaprolactone/polyurethane blends for cardiovascular applications. Acta Biomater. 2011 Jan;7(1):287-94 Authors: Ashton JH, Mertz JA, Harper JL, Slepian MJ, Mills JL, McGrath DV, Vande Geest JP Polymeric endoaortic paving (PEAP) is a process by which a polymer is endovascularly delivered and thermoformed to coat or "pave" the lumen of the aorta. This method may offer an improvement to conventional endoaortic therapy in allowing conformal graft application with reduced risk of endoleak and customization to complex patient geometries. Polycaprolactone (PCL)/polyurethane (PU) blends of various blend ratios were assessed as a potential material for PEAP by characterizing their mechanical, thermoforming and degradation properties. Biaxial tension testing revealed that the blends' stiffness is similar to that of aortic tissue, is higher for blends with more PCL content, and may be affected by thermoforming and degradation. Tubes of blends were able to maintain a higher diameter increase after thermoforming at higher PCL content and higher heating temperatures; 50/50 blend tubes heated to 55 °C were able to maintain 90% of the diameter increase applied. Delamination forces of the blends ranged from 41 to 235 N m⁻². In a Pseudomonas lipase solution, the 50/50 blend had a 94% lower degradation rate than pure PCL, and the 10/90 blend exhibited no degradation. These results indicate that PEAP, consisting of a PCL/PU blend, may be useful in developing the next generation of endoaortic therapy. PMID: 20832506 [PubMed - indexed for MEDLINE] | | | | | | | | | | | | | | | | | | | | | | | | | Effect of molecular weight of chitosan degraded by microwave irradiation on lyophilized scaffold for bone tissue engineering applications. J Biomed Mater Res A. 2011 Feb 11; Authors: Mecwan MM, Rapalo GE, Mishra SR, Haggard WO, Bumgardner JD Chitosan (CTS) is biocompatible, biodegradable, and can be formed into 3D porous structures for bone tissue engineering applications. Although studies have reported on the effects of molecular weight (MW) on CTS physicochemical properties, studies evaluating CTS biological property relationships often do not account for MW that confounds interpretation of study results. The aim of this study was to evaluate the effect of MW on CTS physicochemical and biological properties. CTS materials were treated for 6, 18, and 30 min by microwave irradiation to decrease MW without affecting deacetylation (DDA). Materials were evaluated for crystallinity using X-ray diffraction, thermal degradation using differential scanning calorimetry, water content, swelling ratio, and in vitro compatibility using Saos-2. Results showed that microwave treatments did not affect DDA but decreased MW and swelling ratio by 45.78% and 36.75%, respectively, after 30 min of microwave treatment. Microwave-treated CTS showed reduced or no crystalline peaks. Initial increase in exothermic peak temperatures with short (6 min) microwave treatment times were followed by a decrease with longer (18 and 30 min) treatment times. Cell growth over 7 days on samples was proportional to MW with the number of cells being 62% higher on CTS with the highest MW (3.71 ± 0.25 × 10(5) g/mol) when compared with the lower MW CTS (2.38 ± 0.12 × 10(5) g/mol). These results demonstrate the importance of MW of CTS to both its physicochemical characteristics and biological properties, providing researchers with another tool for the modulation and optimization of CTS for different biomedical applications. © 2011 Wiley Periodicals, Inc. J Biomed Mater Res Part A:, 2011. PMID: 21319294 [PubMed - as supplied by publisher] | | | | | | | | | | | | | | | | | | | | | | | | | Electrospun fiber mats containing shikonin and derivatives with potential biomedical applications. Int J Pharm. 2011 Feb 10; Authors: Kontogiannopoulos KN, Assimopoulou AN, Tsivintzelis I, Panayiotou C, Papageorgiou VP Alkannin, Shikonin (A/S) and their derivatives are naturally occurring hydroxynaphthoquinones with a well-established spectrum of wound healing, antimicrobial, anti-inflammatory, antioxidant and antitumor activity. Clinical studies over the years revealed that A/S derivatives-based wound healing preparations (such as HELIXDERM(®)) are among a very small group of therapeutics that modulate both the inflammatory and proliferative phases of wound healing and present significant tissue regenerative activity. The purpose of the present work was to combine the biological properties of A/S and the advantages of electrospun meshes to prepare a potent topical/transdermal biomaterial for A/S. Four biocompatible polymers (cellulose acetate, poly(L-lactide), poly(lactide-co-glycolide) LA/GA:50/50 and 75/25) were used for the first time, to produce electrospun fiber mats containing either shikonin or A/S mixture in various amounts. Both drugs were effectively loaded into the above biomaterials. The incorporation of drugs did not considerably affect fibers morphology and their mean diameter size varied from 315 to 670nm. High drug entrapment efficiencies (ranged from 74% to 95%) and appropriate release profiles were achieved, that render these fibers as potential A/S topical/transdermal wound healing dressings. Given the multifunctional activity of the natural products alkannins and shikonins, their consideration as bioactive constituents for tissue engineering scaffolds seems a promising strategy for repairing and regenerating tissues and mainly skin. PMID: 21316431 [PubMed - as supplied by publisher] | | | | | | | | | | | | | | | | | | | | | | | | | What we should know before using tissue engineering techniques to repair injured tendons: A developmental biology perspective. Tissue Eng Part B Rev. 2011 Feb 11; Authors: Liu CF, Aschbacher-Smith L, Barthelery N, Dyment N, Butler DL, Wylie C Tendons connect muscles to bones, and serve as the transmitters of force that allow all the movements of the body. Tenocytes are the basic cellular units of tendons, and produce the collagens which form the hierarchical fiber system of the tendon. Tendon injuries are common, and difficult to repair, particularly in the case of the insertion of tendon into bone. Successful attempts at cell based repair therapies will require an understanding of the normal development of tendon tissues, including their differentiated regions such as the fibrous mid-section and fibrocartilaginous insertion site. Many genes are known to be involved in the formation of tendon. However, their functional roles in tendon development have not been fully characterized. Tissue engineers have attempted to generate functional tendon tissue in vitro. However, a lack of knowledge of normal tendon development has hampered these efforts. Here we review studies focusing on the developmental mechanisms of tendon development, and discuss the potential applications of a molecular understanding of tendon development to the treatment of tendon injuries. PMID: 21314435 [PubMed - as supplied by publisher] | | | | | | | | | |  | |  | |  |
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