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Pace LA, Plate JF, Smith TL, Van Dyke ME.
Biomaterials. 2013 Aug ;34(24):5907-14.
PMID: 23680369
Peripheral nerve injuries requiring surgery can be repaired by autograft, the clinical "gold standard", allograft, or nerve conduits. Most published clinical studies show the effectiveness of nerve conduits in small size defects in sensory nerves. Many preclinical studies suggest that peripheral nerve regeneration through conduits can be enhanced and repair lengths increased with the use of a biomaterial filler in the conduit lumen. We have previously shown that a luminal hydrogel filler derived from human hair keratin (HHK) can improve electrophysiological and histological outcomes in mouse, rabbit, and non-human primate nerve injury models, but insight into potential mechanisms has been lacking. Based on the premise that a keratin biomaterial (KOS) hydrogel provides an instantaneous structural matrix within the lumen, the current study compares the cellular behavior elicited by KOS hydrogel to Matrigel (MAT) and saline (SAL) conduit fillers in a 1 cm rat sciatic nerve injury model at early stages of regeneration. While there was little difference in initial cellular influx, the KOS group showed earlier migration of dedifferentiated Schwann cells (SC) from the proximal nerve end compared to the other groups. The KOS group also showed faster SC dedifferentiation and myelin debris clearance, and decreased macrophage infiltration during Wallerian degeneration of the distal nerve tissue.
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Orlando G, Booth C, Wang Z, Totonelli G, Ross CL, Moran E, Salvatori M, Maghsoudlou P, Turmaine M, Delario G, Al-Shraideh Y, Farooq U, Farney AC, Rogers J, Iskandar SS, Burns A, Marini FC, De Coppi P, Stratta RJ, Soker S.
Biomaterials. 2013 Aug ;34(24):5915-25.
PMID: 23680364
In the United States, more than 2600 kidneys are discarded annually, from the total number of kidneys procured for transplant. We hypothesized that this organ pool may be used as a platform for renal bioengineering and regeneration research. We previously showed that decellularization of porcine kidneys yields renal extracellular matrix (ECM) scaffolds that maintain their basic components, support cell growth and welfare in vitro and in vivo, and show an intact vasculature that, when such scaffolds are implanted in vivo, is able to sustain physiological blood pressure. The purpose of the current study was to test if the same strategy can be applied to discarded human kidneys in order to obtain human renal ECM scaffolds. The results show that the sodium dodecylsulfate-based decellularization protocol completely cleared the cellular compartment in these kidneys, while the innate ECM framework retained its architecture and biochemical properties. Samples of human renal ECM scaffolds stimulated angiogenesis in a chick chorioallantoic membrane assay. Importantly, the innate vascular network in the human renal ECM scaffolds retained its compliance. Collectively, these results indicate that discarded human kidneys are a suitable source of renal scaffolds and their use for tissue engineering applications may be more clinically applicable than kidneys derived from animals.
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Dalton GD, Peterson LJ, Howlett AC.
Cell Signal. 2013 Apr 6;25(8):1665-1677.[Epub ahead of print]
PMID: 23571270
Tyrosine phosphorylation (Tyr-P) of focal adhesion kinase (FAK) regulates FAK activation. Phosphorylated FAK Tyr 397 binds Src family kinases (Src), which in turn directly phosphorylate FAK Tyr 576/577 to produce maximal FAK enzymatic activity. CB1 cannabinoid receptors (CB1) are abundantly expressed in the nervous system and influence FAK activation by presently unknown mechanisms. The current investigation determined that CB1-stimulated maximal FAK catalytic activity is mediated by Gi/o proteins in N18TG2 neuronal cells, and that G12/13 regulation of Rac1 and RhoA occurs concomitantly. Immunoblotting analyses using antibodies against FAK phospho-Tyr 397 and phospho-Tyr 576/577 demonstrated that the time-course of CB1-stimulated FAK 576/577 Tyr-P occurred in three phases: Phase I (0-2min) maximal Tyr-P, Phase II (5-20min) rapid decline in Tyr-P, and Phase III (>20min) plateau in Tyr-P at submaximal levels. In contrast, FAK 397 Tyr-P was monophasic and significantly lower in magnitude. FAK 397 Tyr-P and Phase I FAK 576/577 Tyr-P involved protein tyrosine phosphatase (PTP1B and Shp1/Shp2)-mediated Src activation, Protein Kinase A (PKA) inhibition, and integrin activation. Phase I maximal FAK 576/577 Tyr-P also required cooperative signaling between receptor tyrosine kinases (RTKs) and integrins. The integrin antagonist RGDS peptide, Flk-1 vascular endothelial growth factor receptor (VEGFR) antagonist SU5416, and epidermal growth factor receptor (EGFR) antagonist AG 1478 blocked Phase I FAK 576/577 Tyr-P. CB1 agonists failed to stimulate FAK Tyr-P in the absence of integrin activation upon suspension in serum-free culture media. In contrast, cells grown on the integrin ligands fibronectin and laminin displayed increased FAK 576/577 Tyr-P that was augmented by CB1 agonists and blocked by the Src inhibitor PP2 and Flk-1 VEGFR antagonist SU5416. Taken together, these studies have identified a complex integrative pathway utilized by CB1 to stimulate maximal FAK 576/577 Tyr-P in neuronal cells.
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Palmer NR, Geiger AM, Felder TM, Lu L, Case LD, Weaver KE.
Am J Public Health. 2013 May 16. [Epub ahead of print]
PMID: 23678936
Objectives. We examined racial/ethnic disparities in health care receipt among a nationally representative sample of male cancer survivors. Methods. We identified men aged 18 years and older from the 2006-2010 National Health Interview Survey who reported a history of cancer. We assessed health care receipt in 4 self-reported measures: primary care visit, specialist visit, flu vaccination, and pneumococcal vaccination. We used hierarchical logistic regression modeling, stratified by age (< 65 years vs ≥ 65 years). Results. In adjusted models, older African American and Hispanic survivors were approximately twice as likely as were non-Hispanic Whites to not see a specialist (odds ratio [OR] = 1.78; 95% confidence interval [CI] = 1.19, 2.68 and OR = 2.09; 95% CI = 1.18, 3.70, respectively), not receive the flu vaccine (OR = 2.21; 95% CI = 1.45, 3.37 and OR = 2.20; 95% CI = 1.21, 4.01, respectively), and not receive the pneumococcal vaccine (OR = 2.24; 95% CI = 1.54, 3.24 and OR = 3.10; 95% CI = 1.75, 5.51, respectively). Conclusions. Racial/ethnic disparities in health care receipt are evident among older, but not younger, cancer survivors, despite access to Medicare. These survivors may be less likely to see specialists, including oncologists, and receive basic preventive care. (Am J Public Health. Published online ahead of print May 16, 2013: e1-e8. doi:10.2105/AJPH.2012.301096).
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Mirmalek-Sani SH, Orlando G, McQuilling JP, Pareta R, Mack DL, Salvatori M, Farney AC, Stratta RJ, Atala A, Opara EC, Soker S.
Biomaterials. 2013 Jul ;34(22):5488-95.
PMID: 23583038
Emergent technologies of regenerative medicine have the potential to overcome the limitations of organ transplantation by supplying tissues and organs bioengineered in the laboratory. Pancreas bioengineering requires a scaffold that approximates the biochemical, spatial and vascular relationships of the native extracellular matrix (ECM). We describe the generation of a whole organ, three-dimensional pancreas scaffold using acellular porcine pancreas. Imaging studies confirm that our protocol effectively removes cellular material while preserving ECM proteins and the native vascular tree. The scaffold was seeded with human stem cells and porcine pancreatic islets, demonstrating that the decellularized pancreas can support cellular adhesion and maintenance of cell functions. These findings advance the field of regenerative medicine towards the development of a fully functional, bioengineered pancreas capable of establishing and sustaining euglycemia and may be used for transplantation to cure diabetes mellitus.
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Sun X, Kang Y, Bao J, Zhang Y, Yang Y, Zhou X.
Biomaterials. 2013 Jul ;34(21):4971-81.
PMID: 23566802
Osteogenetic microenvironment is a complex constitution in which extracellular matrix (ECM) molecules, stem cells and growth factors each interact to direct the coordinate regulation of bone tissue development. Importantly, angiogenesis improvement and revascularization are critical for osteogenesis during bone tissue regeneration processes. In this study, we developed a three-dimensional (3D) multi-scale system model to study cell response to growth factors released from a 3D biodegradable porous calcium phosphate (CaP) scaffold. Our model reconstructed the 3D bone regeneration system and examined the effects of pore size and porosity on bone formation and angiogenesis. The results suggested that scaffold porosity played a more dominant role in affecting bone formation and angiogenesis compared with pore size, while the pore size could be controlled to tailor the growth factor release rate and release fraction. Furthermore, a combination of gradient VEGF with BMP2 and Wnt released from the multi-layer scaffold promoted angiogenesis and bone formation more readily than single growth factors. These results demonstrated that the developed model can be potentially applied to predict vascularized bone regeneration with specific scaffold and growth factors.
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Kavanagh K, Flynn DM, Jenkins KA, Wilson MD, Chilton FH.
Prostaglandins Leukot Essent Fatty Acids. 2013 May 7. [Epub ahead of print]
PMID: 23664597
Echium oil (EO) contains stearidonic acid (18:4), a n-3 polyunsaturated fatty acids (PUFAs), and gamma-linolenic acids (18:3), a n-6 PUFA that can be converted to long chain (LC)-PUFAs. We aimed to compare a safflower oil (SO)-enriched diet to EO- and fish oil (FO)-enriched diets on circulating and tissue PUFAs levels and glycemic, inflammatory, and cardiovascular health biomarkers in insulin resistant African green monkeys. In a Latin-square cross-over study, eight monkeys consumed matched diets for 6 weeks with 3-week washout periods. Monkeys consuming FO had significantly higher levels of n-3 LC-PUFAs and EO supplementation resulted in higher levels of circulating n-3 LC-PUFAs and a significant increase in dihomo-gamma linolenic acid (DGLA) in red blood cells and muscle. Glucose disposal was improved after EO consumption. These data suggest that PUFAs in EO supplementation have the capacity to alter circulating, RBC and muscle LC-PUFA levels and improve glucose tolerance in insulin-resistant monkeys.
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Vaughan L, Espeland MA, Snively B, Shumaker SA, Rapp SR, Shupe J, Robinson JG, Sarto GE, Resnick SM, .
Brain Res. 2013 Jun 13;1514():3-11.
PMID: 23578696
The Women's Health Initiative Memory Study-Younger (WHIMS-Y) was designed to assess the effect of prior random assignment to hormone therapy (HT) (conjugated equine estrogen (CEE) alone or CEE plus medroxyprogesterone acetate (MPA)) on global cognitive function in younger middle-aged women relative to placebo. WHIMS-Y was an ancillary study to the Women's Health Initiative (WHI) HT trial and enrolled 1361 women who were aged 50-55 years and postmenopausal at WHI enrollment. WHIMS-Y will examine whether an average of 5.4 years of HT during early menopause has longer term protective effects on global cognitive function and if these effects vary by regimen, time between menopause and study initiation, and prior use of HT. We present the study rationale and design. We describe enrollment, adherence to assigned WHI therapy, and compare risk factor characteristics of the WHIMS-Y cohort at the time of WHI enrollment to similar aged women in the WHI HT who did not enroll in WHIMS-Y. Challenges of WHIMS-Y include lower than expected and differential enrollment. Strengths of WHIMS-Y include balance in baseline risk factors between treatment groups, standardized and masked data collection, and high rates of retention and on-trial adherence and exposure. In addition, the telephone-administered cognitive battery showed adequate construct validity. WHIMS-Y provided an unprecedented chance to examine the hypothesis that HT may have protective effects on cognition in younger postmenopausal women aged 50-55 years. Integrated into the WHI, WHIMS-Y optimized the experience of WHI investigators to ensure high retention and excellent quality assurance across sites. This article is part of a Special Issue entitled Hormone Therapy.
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Taheri A, Mansoori P, Al-Dabagh A, Feldman S.
J Dermatolog Treat. 2013 May 20. [Epub ahead of print]
PMID: 23688200
Abstract Background: Superficial second degree skin burns only need re-epithelialization to heal without a scar. After re-epithelialization, inflammation in the dermis contributes to changes in skin architecture and scarring. Suppression of inflammation and fibroblast activation immediately after re-epithelialization may prevent scar formation. Corticosteroids are the mainstay of treatment for keloids and hypertrophic scars. Objective: To assess the available data on use of corticosteroids for prevention of scars. Methods: A review of literature was performed seeking clinical trials using corticosteroids for prevention of scars. Results: Corticosteroids have been used to prevent recurrence after keloid or hypertrophic scar excision with variable success. We did not find any report involving the clinical use of corticosteroids for the prevention of scar formation in other settings, including after skin burns. Conclusion: Theoretically, topical corticosteroids can suppress inflammation and fibroblast activation after skin burn, decreasing the incidence of scar formation. However, there is no study evaluating this hypothesis.
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