The peritoneal cavity as a bioreactor for tissue engineering visceral organs: bladder, uterus and vas deferens

Our objective was to produce avascular, myofibroblast-rich tissue capsules for use as autologous grafts for hollow, smooth muscle-walled visceral organs-bladder, uterus and vas deferens. To produce tissue for grafting, templates of the appropriate shape were implanted in the peritoneal cavities of rats or rabbits. After 2-3 weeks, the templates were removed, the encapsulating myofibroblast-rich tissue harvested and grafted to replace resected segments of bladder, vas deferens or uterus of the same animals in which the tissue was grown. Bladder grafts showed 100% patency after 14 months and had developed a morphology similar to normal bladder. Tubes of myofibroblast tissue grafted unilaterally into resected rabbit vasa deferentia developed a morphology resembling native tissue, with sperm in the ejaculate indicative of normal function. At 12 weeks after grafting, uterine graft tissue had increased in thickness and developed the morphology of normal uterus, with endometrium overlying several layers of smooth muscle cells (myometrium-like) which were interspersed with collagen fibrils; grafted uterine horns supported embryos to the late stages of gestation. This study shows that myofibroblast tissue produced in the peritoneal cavity is sufficiently plastic to permit differentiation of cells into bladder, vas deferens or uterine smooth muscle. As a method for producing autologous graft material for repair/replacement of these organs, this approach has many benefits over conventional and current tissue-engineering strategies.     

Plerixafor, a CXCR4 antagonist for the mobilization of hematopoietic stem cells

Stem cells harvested from peripheral blood are the most commonly used graft source in hematopoietic stem cell transplantation. While G-CSF is the most frequently used agent for stem cell mobilization, the use of G-CSF alone results in suboptimal stem cell yields in a significant proportion of patients undergoing autologous transplantation. Plerixafor (AMD3100, Genzyme Corporation) is a bicyclam molecule that antagonizes the binding of the chemokine stromal cell-derived factor-1 (SDF-1) to its cognate receptor CXCR4. Plerixafor results in the rapid and reversible mobilization of hematopoietic stem cells into the peripheral circulation and is synergistic when combined with G-CSF. In clinical studies of autologous stem cell transplantation, the combination of plerixafor and G-CSF allows the collection of large numbers of stem cells in fewer apheresis sessions and can salvage those who fail G-CSF mobilization alone.     

Neural activity within area V1 reflects unconscious visual performance in a case of blindsight

Although lesions of the striate (V1) cortex disrupt conscious vision, patients can demonstrate surprising residual abilities within their affected visual field, a phenomenon termed blindsight. The relative contribution of spared "islands" of functioning striate cortex to residual vision, versus subcortical pathways to extrastriate areas, has implications for the role of early visual areas in visual awareness and performance. Here we describe the behavioral and neural features of residual cortical function in Patient M.C., who sustained a posterior cerebral artery stroke at the age of 15 years. Within her impaired visual field, we found preserved visual abilities characteristic of blindsight, including superior detection of motion, and above-chance discrimination of shape, color, and motion direction. Functional magnetic resonance imaging demonstrated a retinotopically organized representation of M.C.'s blind visual field within the lesioned occipital lobe, specifically within area V1. The incongruity of a well-organized cortex and M.C.'s markedly impaired vision was resolved by measurement of functional responses within her damaged occipital lobe. Attenuated neural contrast-response functions were found to correlate with M.C.'s impaired psychophysical performance. These results demonstrate that the behavioral features of blindsight may arise in the presence of residual striate responses that are spatially organized and sensitive to contrast variation.     

Inhibitory effects of nordihydroguaiaretic acid (NDGA) on the IGF-1 receptor and androgen dependent growth of LAPC-4 prostate cancer cells

BACKGROUND: Nordihydroguaiaretic acid (NDGA) is an inhibitor of the IGF-1 receptor (IGF-1R) in breast and other cancers, and concomitantly inhibits tumor growth both in cultured cells and animals. The current study evaluates the effect of NDGA on the androgen-stimulated growth of human prostate cancer cells. METHODS: LAPC-4 prostate cancer cells in tissue culture were androgen starved for 3 days, 1 nM dihydrotestosterone (DHT) and other androgens were then added for up to 7 days, and cell proliferation measured. IGF-1R protein expression was measured by Western blot, and IGF-1R mRNA expression by quantitative PCR. IGF-1R receptor kinase activation was measured by ELISA. RESULTS: After 7 days, LAPC-4 growth was doubled by 1 nM DHT. NDGA had a rapid effect to inhibit IGF-1R autophosphorylation induced by IGF-1. DHT increased the expression of IGF-1R protein and mRNA levels. Maximal IGF-1R protein levels were observed 3 days after the addition of androgen. In addition, NDGA, at 10 microM or less, inhibited DHT-induced proliferation in both cells grown in plates and cells grown in soft agar. Androgen receptor (AR) studies by FRET revealed that NDGA had no conformational effects on the AR in response to ligand. CONCLUSIONS: NDGA blocks the DHT-induced growth of LAPC-4 prostate cancer cells by several mechanisms including rapid inhibition of the IGF-1R kinase, and a dose-dependent inhibition of androgen stimulation of IGF-1R expression. Clinical studies of this agent will determine its efficacy in the setting of androgen-dependent prostate cancer.     

The role of lung function in brain tissue oxygenation following traumatic brain injury

OBJECTIVE: Previous studies have demonstrated that periods of low brain tissue oxygen tension (PbtO2) are associated with poor outcome after head trauma but have primarily focused on cerebral and hemodynamic factors as causes of low PbtO2. The purpose of this study was to investigate the influence of lung function on PbtO2 with an oxygen challenge (increase in fraction of inspired oxygen [FiO2] concentration to 1.0). METHODS: This prospective observational cohort study was performed in the neurointensive care unit of the Level 1 trauma center at San Francisco General Hospital. Thirty-seven patients with severe traumatic brain injury (TBI) undergoing brain tissue oxygen monitoring as part of regular care underwent an oxygen challenge, consisting of an increase in FiO2 concentration from baseline to 1.0 for 20 minutes. Partial pressure of arterial oxygen (PaO2), PbtO2, and the ratio of PaO2 to FiO2 (the PF ratio) were determined before and after oxygen challenge. RESULTS: Patients with higher PF ratios achieved greater PbtO2 during oxygen challenge than those with a low PF ratio because they achieved a higher PaO2 after an oxygen challenge. Lung function, specifically the PF ratio, is a major determinant of the maximal PbtO2 attained during an oxygen challenge. CONCLUSIONS: Given that patients with TBI are at risk for pulmonary complications such as pneumonia, severe atelectasis, and adult respiratory distress syndrome, lung function must be considered when interpreting brain tissue oxygenation.