Hematopoietic Stem cell transplantation and lentiviral vector‐based gene therapy for Krabbe's disease: Present convictions and future prospects

Abstract

Currently, presymtomatic hematopoietic stem and progenitor cell transplantation (HSPCT) is the only therapeutic modality that alleviates Krabbe's disease (KD)‐induced central nervous system damage. However, all HSPCT‐treated patients exhibit severe deterioration in peripheral nervous system function characterized by major motor and expressive language pathologies. We hypothesize that a combination of several mechanisms contribute to this phenomenon, including 1) nonoptimal conditioning protocols with consequent inefficient engraftment and biodistribution of donor‐derived cells and 2) insufficient uptake of donor cell‐secreted galactocerebrosidease (GALC) secondary to a naturally low expression level of the cation‐independent mannose 6‐phosphate‐receptor (CI‐MPR). We have characterized the effects of a busulfan (Bu) based conditioning regimen on the efficacy of HSPCT in prolonging twi mouse average life span. There was no correlation between the efficiency of bone marrow engraftment of donor cells and twi mouse average life span. HSPCT prolonged the average life span of twi mice, which directly correlated with the aggressiveness of the Bu‐mediated conditioning protocols. HSPC transduced with lentiviral vectors carrying the GALC cDNA under control of cell‐specific promoters were efficiently engrafted in twi mouse bone marrow. To facilitate HSPCT‐mediated correction of GALC deficiency in target cells expressing low levels of CI‐MPR, a novel GALC fusion protein including the ApoE1 receptor was developed. Efficient cellular uptake of the novel fusion protein was mediated by a mannose‐6‐phosphate‐independent mechanism. The novel findings described here elucidate some of the cellular mechanisms that impede the cure of KD patients by HSPCT and concomitantly open new directions to enhance the therapeutic efficacy of HSPCT protocols for KD. © 2016 The Authors. Journal of Neuroscience Research Published by Wiley Periodicals, Inc.

In vitro Validation of Chimeric β-Galactosylceramidase Enzymes With Improved Enzymatic Activity and Increased Secretion

“…Here, we used optimized transduction protocol resulting in VCN values that are 2-10-fold higher than VCN reported in a previous study evaluating the LV-mediated expression of chimeric GALC enzymes in HSPCs (Hu et al, 2016). Our results show that the addition of the IDSsp and ApoE II peptide did not modify the expression, secretion, or activity of the GALC enzymes in vitro.…”

“…ApoE II shows a higher efficacy as compared to ApoB or ApoE I in enhancing the transport across the BBB of the IDUA enzyme in MPS I mice (Wang et al, 2013) and the enhanced correction of CNS pathology by a chimeric IDS enzyme in a murine model of MPS II (Gleitz et al, 2018). Previous studies reported the generation of chimeric GALC enzymes (Zhang et al, 2008;Hu et al, 2016;Pan et al, 2019). However, their efficacy has been mainly evaluated in cell lines (i.e., 293T, HeLa cells) or fibroblasts (from normal donors and GLD patients), while their safety and efficacy in NPCs, HSPCs, and progeny -therapeutically relevant cells types -has not been extensively studied.…”

“…While previous studies suggest the contribution of the LDLr and LDLr-related proteins (i.e., LRP1, LRP2) to lysosomal enzyme trafficking (Coutinho et al, 2012;Rothaug et al, 2014;Markmann et al, 2015) few of them addressed the potential involvement of these receptors in the cross-correction of relevant LSD cellular models (i.e., CNS cells). Recent studies suggested the MP6r-independent uptake of ApoB-modified sulphamidase (Sorrentino et al, 2013) and ApoE I-modified GALC (Hu et al, 2016) in patient-derived fibroblasts. In contrast, the ApoE II-modified IDS appears to be recaptured preferentially by M6Pr in endothelial-like cells (Gleitz et al, 2018) suggesting that the mechanism of enzyme uptake might be both transgene-and cell type-specific.…”

“…Thus, the use of chimeric GALC enzymes may be key to successfully translate GT approaches to GLD patients. Still, the few studies describing the development of modified GALC enzymes in basic and pre-clinical studies in GLD mice lack a comprehensive assessment of safety and efficacy in therapeutically relevant cell types, i.e., HSPCs and neural cells ( Zhang et al, 2008 ; Hu et al, 2016 ; Pan et al, 2019 ).…”

Biocompatible Polymer Nanoparticles for Drug Delivery Applications in Cancer and Neurodegenerative Disorder Therapies

“…As of today, there is a lack of therapies that can allow an ultimate resolution of LSDs but only symptomatic palliative and supportive treatments. During the past decades, experimental approaches aimed at restoring or substituting the deficient enzymatic activity have been formulated and tested: Enzyme replacement therapy (ERT), gene therapy, and hematopoietic stem cell transplantation are just a few remarkable examples [80,81,82,83,84,85,86,87]. Among these, ERT is the most tested approach as it is based on the periodic injection of human lysosomal enzymes produced by recombinant DNA techniques and then purified.…”