Regenerative Medicine: 3/12 TE-RegenMed-StemCell feed

TE-RegenMed-StemCell feed

[Advances in efficacy and security of expanded mesenchymal stem cells in vitro].

March 11, 2011 at 11:48 AM

[Advances in efficacy and security of expanded mesenchymal stem cells in vitro].

Sheng Wu Gong Cheng Xue Bao. 2010 Dec;26(12):1629-35

Authors: Liu J, Song L, Zou W, Zhuge D, Cui Z

The multipotent differentiation and immunosuppression capability of mesenchymal stem cells (MSCs) make it attractive source for stem cell therapy to treat serious diseases, including neural system diseases and immune disorders. For large scale clinical applications, MSCs have to be expanded to produce sufficient quantity for multiple treatments. While conventional passaging is not appropriate for such a task, bioreactor can be used to expand MSCs more efficiently. Yet the efficacy and biosafety of expanded MSCs must be properly assessed before the expanded MSCs can be implanted. This review presented state-of-the-art in expanding MSCs focusing on the progress on the assessment of the efficacy and biosafety of in vitro expanded MSCs. Current obstacles were discussed and future research directions were outlined.

PMID: 21387824 [PubMed - in process]

Enhanced bone formation in large segmental radial defects by combining adipose-derived stem cells expressing bone morphogenetic protein 2 with nHA/RHLC/PLA scaffold.

March 11, 2011 at 9:27 AM

Enhanced bone formation in large segmental radial defects by combining adipose-derived stem cells expressing bone morphogenetic protein 2 with nHA/RHLC/PLA scaffold.

Int Orthop. 2010 Dec;34(8):1341-9

Authors: Hao W, Dong J, Jiang M, Wu J, Cui F, Zhou D

In this study, rabbit adipose-derived stem cells (rASCs) were isolated, cultured in vitro, and transfected with recombinant adenovirus vector containing human bone morphogenetic protein 2 (Ad-hBMP2). These cells were combined with a nano-hydroxyapatite/recombinant human-like collagen/poly(lactic acid) scaffold (nHA/RHLC/PLA) to fabricate a new biocomposite (hBMP2/rASCs-nHA/RHLC/PLA, group 1) and cultured in osteogenic medium. Non-transfected rASCs mixed with nHA/RHLC/PLA (rASCs-nHA/RHLC/PLA, group 2) and nHA/RHLC/PLA scaffold alone (group 3) served as controls. Scanning electron microscope (SEM) demonstrated integration of rASCs with the nHA/RHLC/PLA scaffold. Quantitative real-time RT-PCR analyses of collagen I, osteonectin, and osteopontin cDNA expression indicated that the osteogenic potency of rASCs was enhanced by transfection with Ad-hBMP2. After in vitro culture for seven days, three groups were implanted into 15-mm length critical-sized segmental radial defects in rabbits. After 12 weeks, radiographic and histological analyses were performed. In group 1, the medullary cavity was recanalised, bone was rebuilt and moulding was finished, the bone contour had begun to remodel and scaffold was degraded completely. In contrast, bone defects were not repaired in groups 2 or 3. Furthermore, the scaffold degradation rate in group 1 was significantly higher than in groups 2 or 3. In summary, after transduction with Ad-hBMP2, the osteogenesis of rASCs was enhanced; a new biocomposite created with these cells induced repair of a critical bone defect in vivo in a relatively short time.

PMID: 20140671 [PubMed - indexed for MEDLINE]

[Isolation, cultivation and identification of adipose-derived stem cell in bovines].

March 11, 2011 at 9:27 AM

[Isolation, cultivation and identification of adipose-derived stem cell in bovines].

Sheng Wu Gong Cheng Xue Bao. 2010 Dec;26(12):1645-51

Authors: Ren Y, Wu H, Ma Y, Cang M, Wang R, Liu D

To obtain bovine adipose-derived stem cells (ADSCs), bovine ADSCs were digested in collagenase type I solution. The growth curve of ADSCs was checked by cell counting. Chromosome analysis was checked. The molecular markers of ADSCs were detected with immunofluorescence staining. The morphology of ADSCs was identical to fibroblast like and the cells showed active proliferative ability. Vimentin, CD49d and CD13 antigens were detected, but CD34 antigen was negative. Alkaline phosphatase activity was greater in ADSCs during calcification, and Alizarin Red staining was positive. Lipid droplets were apparent around cells during adipogenesis, and Oil Red-O staining was positive. The results demonstrated that ADSCs could be used as seed cells for tissue engineering due to the simple isolation, differentiation and stable and active growth.

PMID: 21387826 [PubMed - in process]

Effect of piperacillin-tazobactam coated β-tricalcium phosphate for mastoid obliteration in otitis media.

March 11, 2011 at 9:13 AM

Effect of piperacillin-tazobactam coated β-tricalcium phosphate for mastoid obliteration in otitis media.

Int J Pediatr Otorhinolaryngol. 2011 Mar 7;

Authors: Jang CH, Cho YB, Yang HC, Kim JS, Choi CH, Jang SJ, Park H, Kim GH

BACKGROUND AND OBJECTIVE: β-Tricalcium phosphate (TCP) has good biodegradability and osteoconductivity as a scaffold material for bone tissue engineering. Both block and granular forms are available; however, it has been associated with risk of infection and exposure. To this end, the study evaluated the effect of piperacillin-tazobactam coated β-TCPs for mastoid obliteration in otitis media. MATERIALS AND METHODS: Ten guinea pigs were divided into the experimental (piperacillin-tazobactam coated β-TCP granules, n=5) and control groups (uncoated β-TCP granules, n=5). After mastoid obliteration, transtympanic injection with a saline suspension of lipopolysaccharide established inflammation. The animals were sacrificed 5 weeks later. Tissue sections were stained with hematoxylin and eosin and examined. RESULTS: Encapsulation and formation of fibrous capsule by foreign material in the bulla were not evident. The histological evaluation did not reveal inflammatory cells and fibrosis in the piperacillin-tazobactam coated β-TCP group. In contrast, the control group showed numerous inflammatory cells around the implanted uncoated β-TCP granules and incomplete new bone formation. CONCLUSION: β-TCP is an effective carrier material for piperacillin-tazobactam. The use of piperacillin-tazobactam coated β-TCP may be optimal for mastoid obliteration.

PMID: 21388691 [PubMed - as supplied by publisher]

Chondrogenesis of synovium-derived mesenchymal stem cells in photopolymerizing hydrogel scaffolds.

March 11, 2011 at 9:13 AM

Chondrogenesis of synovium-derived mesenchymal stem cells in photopolymerizing hydrogel scaffolds.

J Biomater Sci Polym Ed. 2010;21(12):1653-67

Authors: Fan J, Ren L, Liang R, Gong Y, Cai D, Wang DA

Recently, tissues adjacent to the wound sites are regarded as a promising therapeutic cell source for curing and repairing purpose. Specifically, therapeutic stem cells have been identified in synovial tissue, a tissue adjacent to articular cartilage. The purpose of this study was to explore therapeutic chondrogenesis with rabbit synovium-derived mesenchymal stem cells (SMSCs) encapsulated in photopolymerized hydrogels. A non-degradable poly(ethylene glycol) diacrylate (PEGDA)-based hydrogel and biodegradable phosphoester-poly(ethylene glycol) (PhosPEG)-based hydrogel were both applied as 3-D scaffolds mediating SMSC chondrogenesis in vitro. The viability of SMSCs in both hydrogels was assessed by fluorescent Live/Dead assay and WST-1 assay. Levels of genes and proteins specific to SMSC chondrogenesis were evaluated by real-time RT-PCR, biochemical analysis and immunohistochemical analysis, respectively. The results demonstrated that SMSCs continue to have a high viability when encapsulated in the hydrogel. By treatment with transforming growth factor (TGF)-beta1 or TGF-beta3, positive SMSC chondrogenesis was successfully achieved in both gels, with the best outcome in the PEGDA system. It can be concluded that both PEGDA and PhosPEG hydrogels are appropriate cell-delivery vehicles for SMSC chondrogenesis. Especially as a biodegradable material, PhosPEG hydrogel displayed great potentials in future applications for articular cartilage regeneration coupling with SMSCs.

PMID: 20537247 [PubMed - indexed for MEDLINE]

Biopolymer-based hydrogels as scaffolds for tissue engineering applications: a review.

March 11, 2011 at 9:13 AM

Biopolymer-based hydrogels as scaffolds for tissue engineering applications: a review.

Biomacromolecules. 2011 Mar 9;

Authors: Van Vlierberghe S, Dubruel P, Schacht E

Hydrogels are physically or chemically crosslinked polymer networks, able to absorb large amounts of water. They can be classified into different categories, depending on various parameters including the preparation method, the charge and the mechanical and structural characteristics. The present review aims to give an overview of hydrogels based on natural polymers and their various applications in the field of tissue engineering. In a first part, relevant parameters describing different hydrogel properties and the strategies applied to finetune these characteristics will be described. In a second part, an important class of biopolymers which possess thermo-sensitive properties (UCST or LCST behaviour) will be discussed. Another part of the review will be devoted to the application of cryogels. Finally, the most relevant biopolymer-based hydrogel systems, the different methods of preparation, as well as an in depth overview of the applications in the field of tissue engineering will be given.

PMID: 21388145 [PubMed - as supplied by publisher]

Tissue-engineered autologous urethras for patients who need reconstruction: an observational study.

March 11, 2011 at 9:13 AM

Tissue-engineered autologous urethras for patients who need reconstruction: an observational study.

Lancet. 2011 Mar 7;

Authors: Raya-Rivera A, Esquiliano DR, Yoo JJ, Lopez-Bayghen E, Soker S, Atala A

BACKGROUND: Complex urethral problems can occur as a result of injury, disease, or congenital defects and treatment options are often limited. Urethras, similar to other long tubularised tissues, can stricture after reconstruction. We aimed to assess the effectiveness of tissue-engineered urethras using patients' own cells in patients who needed urethral reconstruction. METHODS: Five boys who had urethral defects were included in the study. A tissue biopsy was taken from each patient, and the muscle and epithelial cells were expanded and seeded onto tubularised polyglycolic acid:poly(lactide-co-glycolide acid) scaffolds. Patients then underwent urethral reconstruction with the tissue-engineered tubularised urethras. We took patient history, asked patients to complete questionnaires from the International Continence Society (ICS), and did urine analyses, cystourethroscopy, cystourethrography, and flow measurements at 3, 6, 12, 24, 36, 48, 60, and 72 months after surgery. We did serial endoscopic cup biopsies at 3, 12, and 36 months, each time in a different area of the engineered urethras. FINDINGS: Patients had surgery between March 19, 2004, and July 20, 2007. Follow-up was completed by July 31, 2010. Median age was 11 years (range 10-14) at time of surgery and median follow-up was 71 months (range 36-76 months). AE1/AE3, α actin, desmin, and myosin antibodies confirmed the presence of cells of epithelial and muscle lineages on all cultures. The median end maximum urinary flow rate was 27·1 mL/s (range 16-28), and serial radiographic and endoscopic studies showed the maintenance of wide urethral calibres without strictures. Urethral biopsies showed that the engineered grafts had developed a normal appearing architecture by 3 months after implantation. INTERPRETATION: Tubularised urethras can be engineered and remain functional in a clinical setting for up to 6 years. These engineered urethras can be used in patients who need complex urethral reconstruction. FUNDING: National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health.

PMID: 21388673 [PubMed - as supplied by publisher]

[An animal experiment for the regeneration of periodontal defect by application of the dual-release chitosan thermosensitive hydrogel system].

March 11, 2011 at 9:13 AM

[An animal experiment for the regeneration of periodontal defect by application of the dual-release chitosan thermosensitive hydrogel system].

Zhonghua Kou Qiang Yi Xue Za Zhi. 2008 May;43(5):273-7

Authors: Ma ZW, Zhang YJ, Wang R, Wang QT, Dong GY, Wu ZF

To observe the effect of the self-made chitosan thermosensitive hydrogel system with dual-release bone morphogenetic protein and chlorhexidine on periodontal defects repair.

PMID: 18953910 [PubMed - indexed for MEDLINE]

[Isolation, cultivation and identification of adipose-derived stem cell in bovines].

March 11, 2011 at 9:13 AM

[Isolation, cultivation and identification of adipose-derived stem cell in bovines].

Sheng Wu Gong Cheng Xue Bao. 2010 Dec;26(12):1645-51

Authors: Ren Y, Wu H, Ma Y, Cang M, Wang R, Liu D

PMID: 21387826 [PubMed - in process]

Fibrocytes can be reprogrammed to promote tissue remodeling capacity of dermal fibroblasts.

March 11, 2011 at 9:13 AM

Fibrocytes can be reprogrammed to promote tissue remodeling capacity of dermal fibroblasts.

Mol Cell Biochem. 2010 Nov;344(1-2):11-21

Authors: Medina A, Ghahary A

Fibroblasts play a pivotal role in wound healing process participating in both tissue fibrosis and remodeling. However, it remains unclear which factors activate such diversity of fibroblast responses and how this decision-making process is made. Previous reports have demonstrated that wound milieu stimulates the transformation of circulating precursor cells into fibrocytes. These pro-fibrogenic cells promote the collagen production by resident fibroblasts. Conversely, recruited cells with anti-fibrogenic profile that can compete with fibrocytes have not been identified. This report describes a novel transdifferentiation process of fibrocytes induced by changing culture conditions. The reprogrammed fibrocytes markedly increased cell proliferation and MMP-1 expression in dermal fibroblasts. The MMP-1 up-regulation was directly related to the number of fibrocytes that followed this cell transformation. In vitro and in vivo results have confirmed that TGF-β deprivation plays an important role in this novel fibrocyte differentiation pathway. Our findings demonstrate that, changing the fibrocyte commitment, it is possible to exponentially stimulate the tissue remodeling capacity of dermal fibroblasts. These results will open new research approaches to understand the role of cell transdifferentiation and local environment not only in the wound healing process of skin, but also in several other fibrocyte-associated diseases such as lung fibrosis, asthma, liver cirrhosis, chronic pancreatitis, and atherosclerosis.

PMID: 20563835 [PubMed - indexed for MEDLINE]

Vascular smooth muscle enhances functionality of tissue-engineered blood vessels in vivo.

March 11, 2011 at 9:13 AM

Vascular smooth muscle enhances functionality of tissue-engineered blood vessels in vivo.

J Vasc Surg. 2011 Feb;53(2):426-34

Authors: Neff LP, Tillman BW, Yazdani SK, Machingal MA, Yoo JJ, Soker S, Bernish BW, Geary RL, Christ GJ

There is significant room for improvement in the development of tissue-engineered blood vessels (TEBVs) for vascular reconstruction. Most commonly, TEBVs are seeded with endothelial cells (ECs) only. This provides an antithrombogenic surface but suboptimal physiologic characteristics compared with native arteries, due to lack of smooth muscle cells (SMCs) in the vessel media. Although SMCs are critical in vessel architecture and function throughout the vascular tree, few studies have incorporated SMCs in TEBVs implanted in vivo. As such, the goal of the present study was to evaluate the effect of SMC coseeding with ECs on TEBV maturation, structure, and function after prolonged in vivo maturation.

PMID: 20934837 [PubMed - indexed for MEDLINE]

Enhanced bone formation in large segmental radial defects by combining adipose-derived stem cells expressing bone morphogenetic protein 2 with nHA/RHLC/PLA scaffold.

March 11, 2011 at 9:13 AM

Enhanced bone formation in large segmental radial defects by combining adipose-derived stem cells expressing bone morphogenetic protein 2 with nHA/RHLC/PLA scaffold.

Int Orthop. 2010 Dec;34(8):1341-9

Authors: Hao W, Dong J, Jiang M, Wu J, Cui F, Zhou D

PMID: 20140671 [PubMed - indexed for MEDLINE]

[Isolation, culture and identification of rat buccal mucosa stem cells].

March 11, 2011 at 9:13 AM

[Isolation, culture and identification of rat buccal mucosa stem cells].

Zhonghua Kou Qiang Yi Xue Za Zhi. 2008 May;43(5):311-3

Authors: Tao Q, Qiao B, Su K, Lü B, Zheng CQ

To explore a method for isolation and culture Dispase II and Trypsin-EDTA. Cells were seeded onto mitomycin C-treated of rat buccal mucosa stem cells and to identify the stem cells.

PMID: 18953921 [PubMed - indexed for MEDLINE]

Lectin glycoarrays technologies for nanoscale biomedical detection.

March 11, 2011 at 9:13 AM

Lectin glycoarrays technologies for nanoscale biomedical detection.

Protein Pept Lett. 2010;17(11):1417-25

Authors: Chan K, Ng TB

Microarray technologies have begun to feature widely in biomedical science. These techniques, allow for high throughput and quantitative analysis of protein-carbohydrate interactions. Lectin and antibody have been evaluated with these new techniques which extend to the detection of viruses and bacteria. This review outlines some of the basic principles of 'glycoarrays' and illustrates their recent applications. Moreover, the review also gives an overview about a recently launched powerful detection platform using lectin microarrays with a potential to revolutionize the use of lectins in biomedical diagnosis and glycomics in general. In addition, two analytical techniques including mass spectrometry and glycan microarrays expected to play important role to characterize binding profile of new lectins are described in brief. Finally, strong and weak points of lectins as biorecognition molecules currently used in biomedical diagnosis are shown with conclusions drawn from molecular modelling of biorecognition events.

PMID: 20518732 [PubMed - indexed for MEDLINE]

The tumorigenicity of human embryonic and induced pluripotent stem cells.

March 11, 2011 at 6:32 AM

The tumorigenicity of human embryonic and induced pluripotent stem cells.

Nat Rev Cancer. 2011 Mar 10;

Authors: Ben-David U, Benvenisty N

The unique abilities of human pluripotent stem cells to self-renew and to differentiate into cells of the three germ layers make them an invaluable tool for the future of regenerative medicine. However, the same properties also make them tumorigenic, and therefore hinder their clinical application. Hence, the tumorigenicity of human embryonic stem cells (HESCs) has been extensively studied. Until recently, it was assumed that human induced pluripotent stem cells (HiPSCs) would behave like their embryonic counterparts in respect to their tumorigenicity. However, a rapidly accumulating body of evidence suggests that there are important genetic and epigenetic differences between these two cell types, which seem to influence their tumorigenicity.

PMID: 21390058 [PubMed - as supplied by publisher]

Tissue-engineered autologous urethras for patients who need reconstruction: an observational study.

March 11, 2011 at 6:32 AM

Tissue-engineered autologous urethras for patients who need reconstruction: an observational study.

Lancet. 2011 Mar 7;

Authors: Raya-Rivera A, Esquiliano DR, Yoo JJ, Lopez-Bayghen E, Soker S, Atala A

PMID: 21388673 [PubMed - as supplied by publisher]

Direct in vivo cellular reprogramming involves transition through discrete, non-pluripotent steps.

March 11, 2011 at 6:32 AM

Direct in vivo cellular reprogramming involves transition through discrete, non-pluripotent steps.

Development. 2011 Mar 9;

Authors: Richard JP, Zuryn S, Fischer N, Pavet V, Vaucamps N, Jarriault S

Cells can change identity during normal development, in response to tissue damage or defined artificial treatments, or during disease processes such as cancer. Strikingly, not only the reprogramming of tissue cells to an embryonic stem cell-like state, but also the direct conversion from one cell type to another have been described. Direct cell type conversion could represent an alternative strategy for cellular therapies. However, little is known about the actual cellular steps undertaken by a cell as it changes its identity and their possible consequences for the organism. Using an in vivo single-cell system of natural direct reprogramming, in which a C. elegans rectal cell transforms into a motoneuron, we present an in-depth analysis of the cellular transformations involved. We found that the reprogrammed cell transits through intermediate states during direct in vivo reprogramming. We identified and characterised a mutant in the conserved COE transcription factor UNC-3 in which this cellular transformation is blocked. We determined that complete erasure of initial identity first takes place, followed by stepwise, unc-3-dependent, redifferentiation into a motoneuron. Furthermore, unlike in vitro induced reprogramming, reversion to a dedifferentiated identity does not lead to an increase in cellular potential in a natural, in vivo context. Our findings suggest that direct cell type conversion occurs via successive steps, and that dedifferentiation can occur in the absence of cell division. Furthermore, our results suggest that mechanisms are in place in vivo to restrict cell potential during reprogramming, a finding with important implications for regenerative medicine.

PMID: 21389048 [PubMed - as supplied by publisher]

Inhibition of CNS Remyelination by the Presence of Semaphorin 3A.

March 11, 2011 at 6:32 AM

Inhibition of CNS Remyelination by the Presence of Semaphorin 3A.

J Neurosci. 2011 Mar 9;31(10):3719-3728

Authors: Syed YA, Hand E, Möbius W, Zhao C, Hofer M, Nave KA, Kotter MR

Failure of oligodendrocyte precursor cell (OPC) differentiation has been recognized as the leading cause for the failure of myelin regeneration in diseases such as multiple sclerosis (MS). One explanation for the failure of OPC differentiation in MS is the presence of inhibitory molecules in demyelinated lesions. So far only a few inhibitory substrates have been identified in MS lesions. Semaphorin 3A (Sema3A), a secreted member of the semaphorin family, can act as repulsive guidance cue for neuronal and glial cells in the CNS. Recent studies suggest that Sema3A is also expressed in active MS lesions. However, the implication of Sema3A expression in MS lesions remains unclear as OPCs are commonly present in chronic demyelinated lesions. In the present study we identify Sema3A as a potent, selective, and reversible inhibitor of OPC differentiation in vitro. Furthermore, we show that administration of Sema3A into demyelinating lesions in the rat CNS results in a failure of remyelination. Our results imply an important role for Sema3A in the differentiation block occurring in MS lesions.

PMID: 21389227 [PubMed - as supplied by publisher]

Comparison between Drug-Eluting Stents and Coronary Artery Bypass Grafting for Unprotected Left Main Coronary Artery Disease: A Meta-Analysis of Two Randomized Trials and Thirteen Observational Studies.

March 11, 2011 at 6:32 AM

Cardiology. 2011 Mar 11;118(1):22-32

Authors: Zheng S, Zheng Z, Hou J, Hu S

Objective: The clinical outcomes for unprotected left main coronary artery (LMCA) between coronary artery bypass grafting (CABG) and drug-eluting stents (DES) are still controversial. The objective was to compare safety and efficacy between DES and CABG for unprotected LMCA. Methods: Electronic databases and article references were systematically searched (2000-2010) to access relevant studies. Results: Fifteen studies with 5,479 patients were finally involved in the present study. The mortality was similar in DES and CABG groups at 1 year [odds ratio (95% confidence interval): 0.71 (0.5-1.03)], 2 years [1.28 (0.93-1.76)], 3 years [0.88 (0.53-1.46)], 4 years [0.46 (0.18-1.17)], and 5 years [1.16 (0.85-1.57)]. No significant difference was found between DES and CABG in the risk of composite endpoint of death, myocardial infarction and cerebrovascular events during 5 years' follow-up [1 year, 0.95 (0.63-1.43); 2 years, 1.34 (0.67-2.57); 3 years, 1.06 (0.59-1.90); 4 years, 0.53 (0.26-1.08); 5 years, 0.83 (0.33-2.07)]. However, the risk of repeat revascularization was significantly higher in the DES group than the CABG group at 1 year [5.00 (2.85-8.77)], 2 years [4.79 (2.72-8.45)], 3 years [5.72 (3.07-10.65)], 4 years [2.16 (1.17-4.01)], and 5 years [5.65 (3.44-9.27)]. Conclusion: Our meta-analysis indicates that there are no significant differences in the safety between CABG and DES in patients with unprotected LMCA in the 5 years after intervention. But CABG is superior to DES for repeat revascularization.

PMID: 21389717 [PubMed - as supplied by publisher]

Hedgehog/Wnt feedback supports regenerative proliferation of epithelial stem cells in bladder.

March 11, 2011 at 6:32 AM

Hedgehog/Wnt feedback supports regenerative proliferation of epithelial stem cells in bladder.

Nature. 2011 Mar 9;

Authors: Shin K, Lee J, Guo N, Kim J, Lim A, Qu L, Mysorekar IU, Beachy PA

Epithelial integrity in metazoan organs is maintained through the regulated proliferation and differentiation of organ-specific stem and progenitor cells. Although the epithelia of organs such as the intestine regenerate constantly and thus remain continuously proliferative, other organs, such as the mammalian urinary bladder, shift from near-quiescence to a highly proliferative state in response to epithelial injury. The cellular and molecular mechanisms underlying this injury-induced mode of regenerative response are poorly defined. Here we show in mice that the proliferative response to bacterial infection or chemical injury within the bladder is regulated by signal feedback between basal cells of the urothelium and the stromal cells that underlie them. We demonstrate that these basal cells include stem cells capable of regenerating all cell types within the urothelium, and are marked by expression of the secreted protein signal Sonic hedgehog (Shh). On injury, Shh expression in these basal cells increases and elicits increased stromal expression of Wnt protein signals, which in turn stimulate the proliferation of both urothelial and stromal cells. The heightened activity of this signal feedback circuit and the associated increase in cell proliferation appear to be required for restoration of urothelial function and, in the case of bacterial injury, may help clear and prevent further spread of infection. Our findings provide a conceptual framework for injury-induced epithelial regeneration in endodermal organs, and may provide a basis for understanding the roles of signalling pathways in cancer growth and metastasis.

PMID: 21389986 [PubMed - as supplied by publisher]

[Advances in efficacy and security of expanded mesenchymal stem cells in vitro].

March 11, 2011 at 6:32 AM

[Advances in efficacy and security of expanded mesenchymal stem cells in vitro].

Sheng Wu Gong Cheng Xue Bao. 2010 Dec;26(12):1629-35

Authors: Liu J, Song L, Zou W, Zhuge D, Cui Z

PMID: 21387824 [PubMed - in process]

A method for producing transgenic cells using a multi-integrase system on a human artificial chromosome vector.

March 11, 2011 at 6:32 AM

A method for producing transgenic cells using a multi-integrase system on a human artificial chromosome vector.

PLoS One. 2011;6(2):e17267

Authors: Yamaguchi S, Kazuki Y, Nakayama Y, Nanba E, Oshimura M, Ohbayashi T

The production of cells capable of expressing gene(s) of interest is important for a variety of applications in biomedicine and biotechnology, including gene therapy and animal transgenesis. The ability to insert transgenes at a precise location in the genome, using site-specific recombinases such as Cre, FLP, and ΦC31, has major benefits for the efficiency of transgenesis. Recent work on integrases from ΦC31, R4, TP901-1 and Bxb1 phages demonstrated that these recombinases catalyze site-specific recombination in mammalian cells. In the present study, we examined the activities of integrases on site-specific recombination and gene expression in mammalian cells. We designed a human artificial chromosome (HAC) vector containing five recombination sites (ΦC31 attP, R4 attP, TP901-1 attP, Bxb1 attP and FRT; multi-integrase HAC vector) and de novo mammalian codon-optimized integrases. The multi-integrase HAC vector has several functions, including gene integration in a precise locus and avoiding genomic position effects; therefore, it was used as a platform to investigate integrase activities. Integrases carried out site-specific recombination at frequencies ranging from 39.3-96.8%. Additionally, we observed homogenous gene expression in 77.3-87.5% of colonies obtained using the multi-integrase HAC vector. This vector is also transferable to another cell line, and is capable of accepting genes of interest in this environment. These data suggest that integrases have high DNA recombination efficiencies in mammalian cells. The multi-integrase HAC vector enables us to produce transgene-expressing cells efficiently and create platform cell lines for gene expression.

PMID: 21390305 [PubMed - in process]