Corneal scarring from trauma and inflammation disrupts vision for millions worldwide, but corneal transplantation, the primary therapy for corneal blindness, is unavailable to many affected individuals. In this study, stem cells isolated from adult human corneal stroma were examined for the ability to correct stromal opacity in a murine model by direct injection of cells into the corneal stroma. In wild-type mice, injected human stem cells remained viable for months without fusing with host cells or eliciting an immune T-cell response. Human corneal-specific extracellular matrix, including the proteoglycans lumican and keratocan, accumulated in the treated corneas. Lumican-null mice have corneal opacity similar to that of scar tissue as a result of disruption of stromal collagen organization. After injection with human stromal stem cells, stromal thickness and collagen fibril defects in these mice were restored to that of normal mice. Corneal transparency in the treated mice was indistinguishable from that of wild-type mice. These results support the immune privilege of adult stem cells and the ability of stem cell therapy to regenerate tissue in a manner analogous to organogenesis and clearly different from that of normal wound healing. The results suggest that cell-based therapy can be an effective approach to treatment of human corneal blindness.

Bone marrow mesenchymal stromal cells (MSCs) constitute one of the important components of the hematopoietic microenvironmental niche. In vivo studies have shown that depletion of marrow MSCs resulted in reduction of hematopoietic stem cell content, and there is in vitro evidence that marrow MSCs are able to support leukemia progenitor cell proliferation and survival and provide resistance to cytotoxic therapies. How MSCs from leukemia marrow differ from normal counterparts and how they are influenced by the presence of leukemia stem and progenitor cells are still incompletely understood. In this work, we compared normal donor (ND) and acute myelogenous leukemia (AML) derived MSCs and found that AML-MSCs had increased adipogenic potential with improved ability to support survival of leukemia progenitor cells. To identify underlying changes, RNA-Seq analysis was performed. Gene ontology and pathway analysis revealed adipogenesis to be among the set of altered biological pathways dysregulated in AML-MSCs as compared with ND-MSCs. Expression of both SOX9 and EGR2 was decreased in AML-MSCs as compared with ND-MSCs. Increasing expression of SOX9 decreased adipogenic potential of AML-MSCs and decreased their ability to support AML progenitor cells. These findings suggest that AML-MSCs possess adipogenic potential which may enhance support of leukemia progenitor cells.

No abstract

Thyroid eye disease (TED) is a debilitating disorder characterized by the accumulation of adipocytes and hyaluronan (HA).Production of HA by fibroblasts leads to remarkable increases in tissue volume and to the anterior displacement of the eyes. Prostaglandin D 2 (PGD 2 ), mainly produced by mast cells, promotes orbital fibroblast adipogenesis. The mechanism by which PGD 2 influences orbital fibroblasts and their synthesis of HA is poorly understood. We report here that mast cell-derived PGD 2 is a key factor that promotes HA biosynthesis by orbital fibroblasts. Primary orbital fibroblasts from TED patients were isolated and used to test the effects of PGD 2 , prostaglandin J 2 , as well as prostaglandin D receptor (DP) agonists and antagonists on HA synthesis. The expression of HA synthase (HAS), hyaluronidase, DP1, and DP2 mRNA levels was assessed by PCR. Small interfering RNAs against HAS1 or HAS2 were used to assess the importance

TGF␤ induces fibrosis in healing corneal wounds, and in vitro corneal keratocytes up-regulate expression of several fibrosisrelated genes in response to TGF␤. Hyaluronan (HA) accumulates in healing corneas, and HA synthesis is induced by TGF␤ by up-regulation of HA synthase 2. This study tested the hypothesis that HA acts as an extracellular messenger, enhancing specific fibrotic responses of keratocytes to TGF␤. HA synthesis inhibitor 4-methylumbelliferone (4MU) blocked TGF␤ induction of HA synthesis in a concentration-dependent manner. 4MU also inhibited TGF␤-induced up-regulation of ␣-smooth muscle actin, collagen type III, and extra domain A-fibronectin. Chemical analogs of 4MU also inhibited fibrogenic responses in proportion to their inhibition of HA synthesis. 4MU, however, showed no effect on TGF␤ induction of luciferase by the 3TP-Lux reporter plasmid. Inhibition of HA using siRNA to HA synthase 2 reduced TGF␤ up-regulation of smooth muscle actin, fibronectin, and cell division. Similarly, brief treatment of keratocytes with hyaluronidase reduced TGF␤ responses. These results suggest that newly synthesized cell-associated HA acts as an extracellular enhancer of wound healing and fibrosis in keratocytes by augmenting a limited subset of the cellular responses to TGF␤.Keratocytes of the corneal stroma are responsible for the synthesis of the stromal extracellular matrix and thus play an essential role in maintenance of corneal transparency. Under normal in vivo conditions, keratocytes are characteristically quiescent, exhibiting a dendritic morphology with extensive intercellular contacts. In response to stromal injury, such as trauma, keratectomy, or photoablation by excimer laser, keratocytes near the injured site become activated to fibroblasts, altering their morphology, becoming migratory and mitotic, reducing expression of the characteristic keratan sulfate-containing proteoglycans, and eventually transforming into ␣-smooth muscle actin (␣SMA) 4 -expressing myofibroblasts (1).Along with this transition, atypical components of the extracellular matrix are observed, including hyaluronan, biglycan, the extra domain A (EDA) splice form of fibronectin, collagen types I and III, and SPARC (secreted protein acidic and rich in cysteine) (1-5). These fibrotic matrix components contribute to the loss of transparency associated with corneal scars.TGF␤ has been identified as one of the most important factors involved in corneal fibrosis (6). A major function of TGF␤ is to regulate the expression of genes, the products of which contribute to the formation and degradation of extracellular matrix. In monolayer cultures, primary bovine and rabbit keratocytes maintain a dendritic morphology and express corneal keratan sulfate-containing proteoglycans when cultured in serum-free medium. In the presence of TGF␤, keratocytes differentiate into myofibroblasts (2, 3, 7). These cells become mitotic, exhibit a spread morphology, develop focal adhesions, express ␣5␤1 integrin, and develop prominent actin stress fibers conta...