β-Galactosylceramidase Deficiency Causes Bone Marrow Vascular Defects in an Animal Model of Krabbe Disease

Abstract

Krabbe disease (KD) is an autosomal recessive sphingolipidosis caused by the deficiency of the lysosomal hydrolase β-galactosylceramidase (GALC). Oligodendroglia degeneration and demyelination of the nervous system lead to neurological dysfunctions which are usually lethal by two years of age. At present, the only clinical treatment with any proven efficacy is hematopoietic stem-cell transplantation, which is more effective when administered in the neonatal period to presymptomatic recipients. Bone marrow (BM) sinusoidal endothelial cells (SECs) play a pivotal role in stem cell engraftment and reconstitution of hematopoiesis. Previous observations had shown significant alterations of microvascular endothelial cells in the brain of KD patients and in Galc mutant twitcher mice, an authentic model of the disease. In the present study, we investigated the vascular component of the BM in the femurs of symptomatic homozygous twitcher mice at postnatal day P36. Histological, immunohistochemical, and two-photon microscopy imaging analyses revealed the presence of significant alterations of the diaphyseal BM vasculature, characterized by enlarged, discontinuous, and hemorrhagic SECs that express the endothelial marker vascular endothelial growth factor receptor-2 (VEGFR2) but lack platelet/endothelial cell adhesion molecule-1 (CD31) expression. In addition, computer-aided image analysis indicates that twitcher CD31−/VEGFR2+ SECs show a significant increase in lumen size and in the number and size of endothelial gaps compared to BM SECs of wild type littermates. These results suggest that morphofunctional defects in the BM vascular niche may contribute to the limited therapeutic efficacy of hematopoietic stem-cell transplantation in KD patients at symptomatic stages of the disease.

Pentraxin 3 Inhibits the Angiogenic Potential of Multiple Myeloma Cells

“…After euthanasia, mice were transcardially perfused with 0.01 M phosphate-buffered saline (PBS) (Sigma-Aldrich, Milan, Italy) followed by 4% paraformaldehyde (PFA) (VWR). After specimen preparation as previously described [ 26 ], femurs were incubated for 48 h at 4 °C with rabbit anti-mouse KDR (Cell Signaling Technology) and mouse anti-human CD38 (Novocastra) followed by 4 h incubation with AlexaFluor 594 and AlexaFluor488-conjugated secondary antibodies. Then, samples were stored in PBS at 4 °C.…”

Krabbe Disease: Prospects of Finding a Cure Using AAV Gene Therapy

“…These induced globoid cells had reduced CD206 expression and elevated TNF-α and IL-1β cytokine expression profiles ( 61 ). A study selectively knocking out GALC in Schwann cells recapitulated the KD phenotype of fewer and smaller axons in the sciatic nerve of Twitcher mice ( 93 ). A similar approach could be used in better understanding the role of GALC-deficient microglia or astrocytes in disease pathology in the CNS.…”

“…In this regard, both accurate diagnoses of children with KD as well as pre-symptomatic detection are important obstacles to be surmounted. One potential reason for the limited therapeutic efficacy of bone marrow transplantation seen in KD patients at symptomatic stages of the disease could be due to underlying defects in the BM vascular niche as a result of GALC deficiency ( 93 ). There is some evidence that functional BM vasculature may be essential for HSC engraftment ( 105 ).…”