Myelolipoma in the spleen: a rare discovery of extra-adrenal hematopoietic tissue.

Myelolipomas are benign tumors usually found within the adrenal gland. Approximately 50 cases of extra-adrenal myelolipomas have been reported in the literature and all are associated with additional lesions. Myelolipomas contain hematopoetic cells and adipose tissue. Most commonly, they are asymptomatic and are found incidentally on radiologic imaging. Here we report a case of an isolated intrasplenic myelolipoma as an incidental finding during the work up for myasthenia gravis in an otherwise asymptomatic man. The spleen and associated mass were excised during laparotomy and the patient had an uneventful recovery.

Application of the chemokine CXCL12 expression plasmid restores wound healing to near normal in a diabetic mouse model.

BACKGROUND: CXCL12 is a chemokine involved in postinjury leukocyte chemotaxis, migration, and homing of stem cells. We hypothesized that by increasing the level of the chemokine CXCL12 in wounds of diabetic mice, we would increase stem cell recruitment to the wound and, thus, accelerate time to wound closure. METHODS: Eighteen Lepr db-/db- (B6.Cg-m +/+ Leprdb/J; Jackson Labs, Bar Harbor, ME) and their nondiabetic littermates were wounded and treated either with an empty plasmid or a plasmid containing the CXCL12 gene. Wounds were measured approximately every 5 days until they closed completely and were analyzed using planimetry. Wounds were harvested, and relative expression of CXCL12 mRNA was measured using an ABI Prism SDS 7000. To study stem cells affected by this, the plasmid's affect on stem cell recruitment, we used flow cytometry. RESULTS: The diabetic wounds contain a significantly decreased level of CXCL12 mRNA at day 7 postwounding, and these wounds take 55 days to heal. Application of a CXCL12 plasmid to diabetic wounds significantly increases CXCL12 mRNA at day 7, and these wounds heal in 23 days. CONCLUSIONS: Lack of CXCL12 in diabetic wounds contributes to delayed wound healing and can be reversed via single application of a CXCL12-containing plasmid.

Secretion of SDF-1alpha by bone marrow-derived stromal cells enhances skin wound healing of C57BL/6 mice exposed to ionizing radiation.

Patients treated for cancer therapy using ionizing radiation (IR) have delayed tissue repair and regeneration. The mechanisms mediating these defects remain largely unknown at present, thus limiting the development of therapeutic approaches. Using a wound healing model, we here investigate the mechanisms by which IR exposure limits skin regeneration. Our data show that induction of the stromal cell-derived growth factor 1alpha (SDF-1alpha) is severely impaired in the wounded skin of irradiated, compared to non-irradiated, mice. Hence, we evaluated the potential of bone marrow-derived multipotent stromal cells (MSCs), which secrete high levels of SDF-1alpha, to improve skin regeneration in irradiated mice. Injection of MSCs into the wound margin led to remarkable enhancement of skin healing in mice exposed to IR. Injection of irradiated MSCs into the wound periphery of non-irradiated mice delayed wound closure, also suggesting an important role for the stromal microenvironment in skin repair. The beneficial actions of MSCs were mainly paracrine, as the cells did not differentiate into keratinocytes. Specific knockdown of SDF-1alpha expression led to drastically reduced efficiency of MSCs in improving wound closure, indicating that SDF-1alpha secretion by MSCs is largely responsible for their beneficial action. We also found that one mechanism by which SDF-1alpha enhances wound closure likely involves increased skin vascularization. Our findings collectively indicate that SDF-1alpha is an important deregulated cytokine in irradiated wounded skin, and that the decline in tissue regeneration potential following IR can be reversed, given adequate microenvironmental support.

HOXA3 modulates injury-induced mobilization and recruitment of bone marrow-derived cells.

The regulated recruitment and differentiation of multipotent bone marrow-derived cells (BMDCs) to sites of injury are critical for efficient wound healing. Previously we demonstrated that sustained expression of HOXA3 both accelerated wound healing and promoted angiogenesis in diabetic mice. In this study, we have used green fluorescent protein-positive bone marrow chimeras to investigate the effect of HOXA3 expression on recruitment of BMDCs to wounds. We hypothesized that the enhanced neovascularization induced by HOXA3 is due to enhanced mobilization, recruitment, and/or differentiation of BMDCs. Here we show that diabetic mice treated with HOXA3 displayed a significant increase in both mobilization and recruitment of endothelial progenitor cells compared with control mice. Importantly, we also found that HOXA3-treated mice had significantly fewer inflammatory cells recruited to the wound compared with control mice. Microarray analyses of HOXA3-treated wounds revealed that indeed HOXA3 locally increased expression of genes that selectively promote stem/progenitor cell mobilization and recruitment while also suppressing expression of numerous members of the proinflammatory nuclear factor kappaB pathway, including myeloid differentiation primary response gene 88 and toll-interacting protein. Thus HOXA3 accelerates wound repair by mobilizing endothelial progenitor cells and attenuating the excessive inflammatory response of chronic wounds.