Secretion and organization of a cornea-like tissue in vitro by stem cells from human corneal stroma
INVESTIGATIVE OPHTHALMOLOGY & VISUAL SCIENCE
Authors: Du, Yiqin; SundarRaj, Nirmala; Funderburgh, Martha L.; Harvey, Stephen A.; Birk, David E.; Funderburgh, James L.
Abstract
PURPOSE. To investigate the potential of human corneal stromal stem cells to assume a keratocyte phenotype and to organize extracellular matrix ( ECM) in vitro similar to corneal stromal tissue. METHODS. Human corneal stromal stem cells ( hCSSC) were isolated as side population cells by flow cytometry. Cloned hCSSC were cultured as free-floating pellets in serum-free media for 3 weeks. Gene expression was examined using gene array, quantitative RT-PCR, immunostaining, and immunoblotting. Transmission electron microscopy showed collagen fibril size and alignment. RESULTS. Pellet cultures of hCSSC in serum-free media upregulated the expression of keratocyte-specific genes and secreted substantial ECM containing characteristic stromal components: keratocan, keratan sulfate, collagen I, collagen V, and collagen VI. Abundant connexin 43 and cadherin 11 in pellets demonstrated cell-cell junctions typical of keratocytes in vivo. Electron microscopy of the pellet cultures revealed abundant fibrillar collagen, some of which was aligned in parallel arrays similar to those of stromal lamellae. Gene array identified expression in pellets of several genes highly expressed by keratocytes. Transcripts for these keratocyte genes FLJ30046, KERA, ALDH3A1, CXADR, PTGDS, PDK4, MTAC2D1, F13A1 - were increased by as much as 100-fold in pellets compared with hCSSC. Simultaneously, expression of stem cell genes BMI1, KIT, NOTCH1, SIX2, PAX6, ABCG2, SPAG10, and OSIL was reduced by a similar factor in pellets compared with hCSSC. CONCLUSIONS. Scaffolding-free pellet culture of hCSSC induces keratocyte gene expression patterns in these cells and secretion of an organized stroma-like ECM. These cells offer a novel potential for corneal bioengineering.
Genome-wide scan for quantitative trait loci influencing LDL size and plasma triglyceride in familial hypertriglyceridemia
JOURNAL OF LIPID RESEARCH
Authors: Austin, MA; Edwards, KL; Monks, SA; Koprowicz, KM; Brunzell, JD; Motulsky, AG; Mahaney, MC; Hixson, JE
Abstract
Small, dense LDLs and hypertriglyceridemia, two highly correlated and genetically influenced risk factors, are known to predict for risk of coronary heart disease. The objective of this study was to perform a whole-genome scan for linkage to LDL size and triglyceride (TG) levels in 26 kindreds with familial hypertriglyceridemia (FHTG). LDL size was estimated using gradient gel electrophoresis, and genotyping was performed for 355 autosomal markers with an average heterozygosity of 76% and an average spacing of 10.2 centimorgans (cMs). Using variance components linkage analysis, one possible linkage was found for LDL size [logarithm of odds (LOD) = 2.1] on chromosome 6, peak at 140 cM distal to marker F13A1 (closest marker D6S2436). With adjustment for TG and/or HDL cholesterol, the LOD scores were reduced, but remained in exactly the same location. For TG, LOD scores of 2.56 and 2.44 were observed at two locations on chromosome 15, with peaks at 29 and 61 cM distal to marker D15S822 (closest markers D15S643 and D15S211, respectively). These peaks were retained with adjustment for LDL size and/or HDL cholesterol.jlr These findings, if confirmed, suggest that LDL particle size and plasma TG levels could be caused by two different genetic loci in FUTG.-Austin, M. A., K. L. Edwards, S. A. Monks, K. M. Koprowicz,J. D. Brunzell, A. G. Motulsky, M. C. Mahaney, and J. E. Hixson. Genome-wide scan for quantitative trait loci influencing LDL size and plasma triglyceride in familial hypertriglyceridemia.