| High-Throughput FACS Purification of Transduced Progenitors Expressing Defined VEGF Levels Induces Controlled Angiogenesis In Vivo.
December 30, 2009 at 6:44 am
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| | High-Throughput FACS Purification of Transduced Progenitors Expressing Defined VEGF Levels Induces Controlled Angiogenesis In Vivo. Stem Cells. 2009 Dec 28; Authors: Misteli H, Wolff T, Füglistaler P, Gianni-Barrera R, Gürke L, Heberer M, Banfi A Delivery of therapeutic genes by genetically modified progenitors is a powerful tool for regenerative medicine. However, many proteins remain localized within or around the expressing cell and heterogeneous expression levels can lead to reduced efficacy or increased toxicity. For example, the matrix-binding Vascular Endothelial Growth Factor (VEGF) can induce normal, stable and functional angiogenesis or aberrant angioma growth depending on its level of expression in the microenvironment around each producing cell, and not on its total dose. To overcome this limitation, we developed a flow cytometry-based method to rapidly purify transduced cells expressing desired levels of a therapeutic transgene. Primary mouse myoblasts were transduced with a bicistronic retrovirus expressing VEGF linked to a non-functional, truncated form of the syngenic molecule CD8a. By using a clonal population uniformly expressing a known VEGF level as a reference, cells producing similar VEGF amounts were rapidly sorted from the primary population based on their CD8a fluorescence intensity. A single round of sorting with a suitably designed gate yielded a purified population that induced robust, normal and stable angiogenesis, and completely avoided angioma growth, which was instead always caused by the heterogeneous parent population. This clinically applicable high-throughput technique allowed the delivery of highly controlled VEGF levels in vivo, leading to significantly improved safety without compromising efficacy. Furthermore, when applied to other suitable progenitor populations, this technique could help overcome a significant obstacle in the development of safe and efficacious vascularization strategies in the fields of regenerative medicine and tissue engineering. PMID: 20039367 [PubMed - as supplied by publisher] |
| Tissue-Tissue Interactions During Morphogenesis of the Outflow Tract.
December 30, 2009 at 6:44 am
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| | Tissue-Tissue Interactions During Morphogenesis of the Outflow Tract. Pediatr Cardiol. 2009 Dec 29; Authors: Rentschler S, Jain R, Epstein JA The heart forms as a linear heart tube that loops and septates to produce a mature four-chambered structure. The single vessel emerging from the embryonic heart, the truncus arteriosus, divides into the aorta and the pulmonary artery as part of this septation process, and a series of additional morphogenetic events result in the proper alignment and orientation of the cardiac outflow tract. Recent evidence indicates that this process involves the complex interactions of multiple cell types including primary and secondary heart fields, neural crest, pharyngeal mesenchyme, endoderm, and endothelium. Among the many signals that mediate tissue-tissue interactions during the formation of the outflow tract, we have focused on the role of the Notch signaling pathway. Here, we focus on recent advances in our understanding of Notch-mediated regulation of cardiac development with specific attention to the formation of the cardiac outflow tract. PMID: 20039033 [PubMed - as supplied by publisher] |
| Restricted ethnic diversity in human embryonic stem cell lines.
December 30, 2009 at 6:44 am
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| | Restricted ethnic diversity in human embryonic stem cell lines. Nat Methods. 2010 Jan;7(1):6-7 Authors: Laurent LC, Nievergelt CM, Lynch C, Fakunle E, Harness JV, Schmidt U, Galat V, Laslett AL, Otonkoski T, Keirstead HS, Schork A, Park HS, Loring JF PMID: 20038950 [PubMed - in process] |
| [Updates on ossification of posterior longitudinal ligament. Ossification front of posterior longitudinal ligament and cellular biological assessment of chronic mechanical compressed spinal cord]
December 30, 2009 at 6:44 am
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| | [Updates on ossification of posterior longitudinal ligament. Ossification front of posterior longitudinal ligament and cellular biological assessment of chronic mechanical compressed spinal cord] Clin Calcium. 2009 Oct;19(10):1472-9 Authors: Uchida K, Nakajima H, Yayama T, Sato R, Baba H Mechanisms of ossification processes, pathological changes, and treatment/assessment of myelopathy symptoms because of ossification of the posterior longitudinal ligament (OPLL) remain obscure. Enchondral ossification process of OPLL was closely associated with degenerative changes of elastic fibers and cartilage formation, together with the appearance of metaplastic hypertrophic cartilage cells and neovascularization. There are differences in expression degrees of cytokines and transcription factors between mixed and localized OPLL. While the chronic compressed spinal cord may have plasticity ; the use of stem cell implants, supplementation of neurotrophic factors, in addition to surgical treatment, may bring a better clinical outcome,encouraging the development of these basic research studies. Assessment using new imaging techniques needs to determine the affected level and judge the severity of symptoms. PMID: 19794256 [PubMed - indexed for MEDLINE] |
| A cell leakproof PLGA-collagen hybrid scaffold for cartilage tissue engineering.
December 30, 2009 at 6:32 am
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| | A cell leakproof PLGA-collagen hybrid scaffold for cartilage tissue engineering. Biotechnol Prog. 2009 Dec 28; Authors: Kawazoe N, Inoue C, Tateishi T, Chen G A cell leakproof porous poly(DL-lactic-co-glycolic acid) (PLGA)-collagen hybrid scaffold was prepared by wrapping the surfaces of a collagen sponge except the top surface for cell seeding with a bi-layered PLGA mesh. The PLGA-collagen hybrid scaffold had a structure consisting of a central collagen sponge formed inside a bi-layered PLGA mesh cup. The hybrid scaffold showed high mechanical strength. The cell seeding efficiency was 90.0% when human mesenchymal stem cells (MSCs) were seeded in the hybrid scaffold. The central collagen sponge provided enough space for cell loading and supported cell adhesion, while the bi-layered PLGA mesh cup protected against cell leakage and provided high mechanical strength for the collagen sponge to maintain its shape during cell culture. The MSCs in the hybrid scaffolds showed round cell morphology after 4 weeks culture in chondrogenic induction medium. Immunostaining demonstrated that type II collagen and cartilaginous proteoglycan were detected in the extracellular matrices. Gene expression analyses by real-time PCR showed that the genes encoding type II collagen, aggrecan, and SOX9 were upregulated. These results indicated that the MSCs differentiated and formed cartilage-like tissue when being cultured in the cell leakproof PLGA-collagen hybrid scaffold. The cell leakproof PLGA-collagen hybrid scaffolds should be useful for applications in cartilage tissue engineering. (c) 2009 American Institute of Chemical Engineers Biotechnol. Prog., 2010. PMID: 20039440 [PubMed - as supplied by publisher] |
| High-Throughput FACS Purification of Transduced Progenitors Expressing Defined VEGF Levels Induces Controlled Angiogenesis In Vivo.
December 30, 2009 at 6:32 am
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| | High-Throughput FACS Purification of Transduced Progenitors Expressing Defined VEGF Levels Induces Controlled Angiogenesis In Vivo. Stem Cells. 2009 Dec 28; Authors: Misteli H, Wolff T, Füglistaler P, Gianni-Barrera R, Gürke L, Heberer M, Banfi A Delivery of therapeutic genes by genetically modified progenitors is a powerful tool for regenerative medicine. However, many proteins remain localized within or around the expressing cell and heterogeneous expression levels can lead to reduced efficacy or increased toxicity. For example, the matrix-binding Vascular Endothelial Growth Factor (VEGF) can induce normal, stable and functional angiogenesis or aberrant angioma growth depending on its level of expression in the microenvironment around each producing cell, and not on its total dose. To overcome this limitation, we developed a flow cytometry-based method to rapidly purify transduced cells expressing desired levels of a therapeutic transgene. Primary mouse myoblasts were transduced with a bicistronic retrovirus expressing VEGF linked to a non-functional, truncated form of the syngenic molecule CD8a. By using a clonal population uniformly expressing a known VEGF level as a reference, cells producing similar VEGF amounts were rapidly sorted from the primary population based on their CD8a fluorescence intensity. A single round of sorting with a suitably designed gate yielded a purified population that induced robust, normal and stable angiogenesis, and completely avoided angioma growth, which was instead always caused by the heterogeneous parent population. This clinically applicable high-throughput technique allowed the delivery of highly controlled VEGF levels in vivo, leading to significantly improved safety without compromising efficacy. Furthermore, when applied to other suitable progenitor populations, this technique could help overcome a significant obstacle in the development of safe and efficacious vascularization strategies in the fields of regenerative medicine and tissue engineering. PMID: 20039367 [PubMed - as supplied by publisher] |
| Biomaterials for bone regeneration.
December 30, 2009 at 6:32 am
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| | Biomaterials for bone regeneration. Med Oral Patol Oral Cir Bucal. 2009 Dec 29; Authors: Pérez-Sánchez MJ, Ramírez-Glindon E, Lledó-Gil M, Calvo-Guirado JL, Pérez-Sánchez C Objective: this article reviews the literature on biomaterials used for bone regeneration. Material and method: a total of seventeen bibliographic sources were found using the MEDLINE database and to avoid the variability of the search terms the thesaurus Mesh was used. Results: these materials act essentially due to their osteoconductive ability, although their osteoinductive capacity is being improved with the use of growth factors. As to their effectiveness, many differences exist between them and some even affect bone regeneration negatively. Conclusions: biomaterials used for bone regeneration are valid when the correct material is used. As yet the osteogenic capacity of autogenous bone has not been equalled by biomaterials. Tissue engineering has caused great interest because of its many possibilities, although more studies are necessary in order to achieve the ambitious expectations when it comes to tissue or organ regeneration in the human body. PMID: 20038898 [PubMed - as supplied by publisher] |
| Influence of decreasing nutrient path length on the development of engineered cartilage.
December 30, 2009 at 6:32 am
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| | Influence of decreasing nutrient path length on the development of engineered cartilage. Osteoarthritis Cartilage. 2009 May;17(5):677-85 Authors: Bian L, Angione SL, Ng KW, Lima EG, Williams DY, Mao DQ, Ateshian GA, Hung CT OBJECTIVE: Chondrocyte-seeded agarose constructs of 4mm diameter (2.34 mm thickness) develop spatially inhomogeneous material properties with stiffer outer edges and a softer central core suggesting nutrient diffusion limitations to the central construct region [Guilak F, Sah RL, Setton LA. Physical regulation of cartilage metabolism. In: Mow VC, Hayes WC, Eds. Basic Orthopaedic Biomechanics, Philadelphia 1997;179-207.]. The effects of reducing construct thickness and creating channels running through the depth of the thick constructs were examined. METHODS: In Study 1, the properties of engineered cartilage of 0.78 mm (thin) or 2.34 mm (thick) thickness were compared. In Study 2, a single nutrient channel (1 mm diameter) was created in the middle of each thick construct. In Study 3, the effects of channels on larger 10 mm diameter, thick constructs were examined. RESULTS: Thin constructs developed superior mechanical and biochemical properties than thick constructs. The channeled constructs developed significantly higher mechanical properties vs control channel-free constructs while exhibiting similar glycosaminoglycan (GAG) and collagen content. Collagen staining suggested that channels resulted in a more uniform fibrillar network. Improvements in constructs of 10 mm diameter were similarly observed. CONCLUSIONS: This study demonstrated that more homogeneous tissue-engineered cartilage constructs with improved mechanical properties can be achieved by reducing their thickness or incorporating macroscopic nutrient channels. Our data further suggests that these macroscopic channels remain open long enough to promote this enhanced tissue development while exhibiting the potential to refill with cell elaborated matrix with additional culture time. Together with reports that <3 mm defects in cartilage heal in vivo and that irregular holes are associated with clinically used osteochondral graft procedures, we anticipate that a strategy of incorporating macroscopic channels may aid the development of clinically relevant engineered cartilage with functional properties. PMID: 19022685 [PubMed - indexed for MEDLINE] |
| [Preparation of porcine acellular dermal matrix by low concentration of trypsin digestion and repeated freeze-thaw cycles]
December 30, 2009 at 6:32 am
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| | [Preparation of porcine acellular dermal matrix by low concentration of trypsin digestion and repeated freeze-thaw cycles] Zhonghua Shao Shang Za Zhi. 2004 Dec;20(6):354-6 Authors: Tan Q, Zou ZT, Ning GS, Lin ZH, Zhou HR, Liang ZW, Chen X, Wu JM OBJECTIVE: To establish a new method for the preparation of porcine acellular dermal matrix. METHODS: The antigenicity of the porcine dermis was weakened by removing epidermal and dermal cells from the porcine skin through the digestion with low-concentration trypsin and repeated freeze-thaw cycles. Split thickness porcine skin was treated with 0.05% trypsin to remove the cells from the epidermis and dermis. Repeated freeze-thaw cycles were employed to further weed out the residual cells within the dermis. The prepared acellular dermis was then examined grossly, as well as histologically, and also by immunohistochemical method. RESULTS: No cell could be identified in the prepared porcine acellular dermal matrix. The integral basement membrane was preserved on the surface of dermal matrix with compact dermal matrix collagen structure. CONCLUSION: Low concentration trypsinization and repeated freeze-thaw cycles seemed to be a simple and effective method for the preparation of xenogeneic acellular dermal matrix. PMID: 15730686 [PubMed - indexed for MEDLINE] | | | 
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