Coexpression of recombinant adenovirus carrying GDNF and EDNRB genes in neural stem cells in vitro

Gastrointestinal Neuropathies: New Insights and Emerging Therapies

The bewildering complexity of the enteric nervous system makes it susceptible to develop a wide array of motility disorders, collectively called enteric neuropathies. These gastrointestinal conditions are among the most challenging to manage, mainly given poor characterization of their etiopathophysiology and outcomes. Not surprisingly, therefore, targeted or curative therapies for enteric neuropathies are lacking and management is largely symptomatic. Nonetheless, recent advances in neurogastroenterology have witnessed improvements in established strategies, such as intestinal transplantation and the emergence of new treatments including novel drugs, electrical pacing, and manipulation of fecal microbiota, as well as stem cell and gene therapy.

Sustained delivery of glial cell-derived neurotrophic factors in collagen conduits for facial nerve regeneration

Facial nerve injury caused by traffic accidents or operations may reduce the quality of life in patients, and recovery following the injury presents unique clinical challenges. Glial cell-derived neurotrophic factor (GDNF) is important in nerve regeneration; however, soluble GDNF rapidly diffuses into body fluids, making it difficult to achieve therapeutic efficacy. In this work, we developed a rat tail derived collagen conduit to connect nerve defects in a simple and safe manner. GDNF was immobilized in the collagen conduits via chemical conjugation to enable controlled release of GDNF. The GDNF delivery system prevented rapid diffusion from the site without impacting bioactivity of GDNF; degradation of the collagen conduit was inhibited owing to the chemical conjugation. The artificial nerve conduit was then used to examine facial nerve regeneration across a facial nerve defect. Following transplantation, the artificial nerve conduits degraded gradually without causing dislocations and serious inflammation, with good integration into the host tissue. Functional and histological tests indicated that the artificial nerve conduits were able to guide the axons to grow through the defect, reaching the distal stumps. The degree of nerve regeneration in the group that was treated with the artificial nerve conduit approached that of the autograft group, and exceeded that of the other conduit grafted groups.

STATEMENT OF SIGNIFICANCE

In this study, we developed artificial nerve conduits consisting of GDNF immobilized on collagen, with the aim of providing an environment for nerve regeneration. Our results show that the artificial nerve conduits guided the regeneration of axons to the distal nerve segment. GDNF was immobilized stably in the artificial nerve conduits, and therefore retained a sufficient concentration at the target site to effectively promote the regeneration process. The artificial nerve conduits exhibited good biocompatibility and facilitated nerve regeneration and functional recovery with an efficacy that was close to that of an autograft, and better than that of the other conduit grafted groups. Our approach provides an effective delivery system that overcomes the rapid diffusion of GDNF in body fluids, promoting peripheral nerve regeneration. The artificial nerve conduit therefore qualifies as a putative candidate material for the fabrication of peripheral nerve reconstruction devices.

Isogenic enteric neural progenitor cells can replace missing neurons and glia in mice with Hirschsprung disease

BACKGROUND

Transplanting autologous patient-derived enteric neuronal stem/progenitor cells (ENSCs) is an innovative approach to replacing missing enteric neurons in patients with Hirschsprung disease (HSCR). Using autologous cells eliminates immunologic and ethical concerns raised by other cell sources. However, whether postnatal aganglionic bowel is permissive for transplanted ENSCs and whether ENSCs from HSCR patients can be successfully isolated, cultured, and transplanted in vivo remains unknown.

METHODS

ENSCs isolated from the ganglionic intestine of Ednrb(-/-) mice (HSCR-ENSCs) were characterized immunohistochemically and evaluated for their capacity to proliferate and differentiate in vitro. Fluorescently labeled ENSCs were co-cultured ex vivo with aganglionic Ednrb(-/-) colon. For in vivo transplantation, HSCR-ENSCs were labeled with lentivirus expressing green fluorescent protein (GFP) and implanted into aganglionic embryonic chick gut in ovo and postnatal aganglionic Ednrb(-/-) rectum in vivo.

KEY RESULTS

HSCR-ENSCs maintain normal capacity self-renewal and neuronal differentiation. Moreover, the Ednrb(-/-) aganglionic environment is permissive to engraftment by wild-type ENSCs ex vivo and supports migratrion and neuroglial differentiation of these cells following transplantation in vivo. Lentiviral GFP-labeled HSCR-ENSCs populated embryonic chick hindgut and postnatal colon of Ednrb(-/-) HSCR, with cells populating the intermuscular layer and forming enteric neurons and glia.

CONCLUSIONS & INFERENCES

ENSCs can be isolated and cultured from mice with HSCR, and transplanted into the aganglionic bowel of HSCR littermates to generate enteric neuronal networks. These results in an isogenic model establish the potential of using autologous-derived stem cells to treat HSCR and other intestinal neuropathies.

Lentiviral labeling of mouse and human enteric nervous system stem cells for regenerative medicine studies

BACKGROUND

Reliable methods of labeling human enteric nervous system (ENS) stem cells for use in novel cell replacement therapies for enteric neuropathies are lacking. Here, we explore the possibility of using lentiviral vectors expressing fluorescent reporter genes to transduce, label, and trace mouse and human ENS stem cells following transplantation into mouse gut.

METHODS

Enteric nervous system precursors, including ENS stem cells, were isolated from enzymatically dissociated mouse and human gut tissues. Lentivirus containing eGFP or mCherry fluorescent reporter genes was added to gut cell cultures at a multiplicity of infection of 2-5. After fluorescence activated cell sorting for eGFP and subsequent analysis with markers of proliferation and cell phenotype, transduced mouse and human cells were transplanted into the gut of C57BL/6 and immune deficient Rag2-/gamma chain-/C5 mice, respectively and analyzed up to 60 days later.

KEY RESULTS

Mouse and human transduced cells survived in vitro, maintained intense eGFP expression, proliferated as shown by BrdU incorporation, and formed characteristic neurospheres. When transplanted into mouse gut in vivo and analyzed up to 2 months later, transduced mouse and human cells survived, strongly expressed eGFP and integrated into endogenous ENS networks.

CONCLUSIONS & INFERENCES

Lentiviral vectors expressing fluorescent reporter genes enable efficient, stable, long-term labeling of ENS stem cells when transplanted into in vivo mouse gut. This lentiviral approach not only addresses the need for a reliable fluorescent marker of human ENS stem cells for preclinical studies, but also raises the possibility of using lentiviruses for other applications, such as gene therapy.

Migration and differentiation of transplanted enteric neural crest-derived cells in murine model of Hirschsprung's disease

Stem cell therapy offers the potential of rebuilding the enteric nervous system (ENS) in the aganglionic bowel of patients with Hirschsprung's disease. P0-Cre/Floxed-EGFP mice in which neural crest-derived cells express EGFP were used to obtain ENS stem/progenitor cells. ENS stem/progenitor cells were transplanted into the bowel of Ret(-/-) mouse, an animal model of Hirschsprung's disease. Immunohistochemical analysis was performed to determine whether grafted cells gave rise to neurons in the recipient bowel. EGFP expressing neural crest-derived cells accounted for 7.01 ± 2.52 % of total cells of gastrointestinal tract. ENS stem/progenitor cells were isolated using flow cytometry and expanded as neurosphere-like bodies (NLBs) in a serum-free culture condition. Some cells in NLBs expressed neural crest markers, p75 and Sox10 and neural stem/progenitor cells markers, Nestin and Musashi1. Multipotency of isolated ENS stem/progenitor cells was determined as they differentiated into neurons, glial cells, and myofibloblasts in culture. When co-cultured with explants of hindgut of Ret(-/-) mice, ENS stem/progenitor cells migrated into the aganglionic bowel and gave rise to neurons. ENS stem/progenitor cells used in this study appear to be clinically relevant donor cells in cell therapy to treat Hirschsprung's disease capable of colonizing the affected bowel and giving rise to neurons.

Neural stem cell therapies for enteric nervous system disorders

The enteric nervous system is vulnerable to a range of congenital and acquired disorders that disrupt the function of its neurons or lead to their loss. The resulting enteric neuropathies are some of the most challenging clinical conditions to manage. Neural stem cells offer the prospect of a cure given their potential ability to replenish missing or dysfunctional neurons. This article discusses diseases that might be targets for stem cell therapies and the barriers that could limit treatment application. We explore various sources of stem cells and the proof of concept for their use. The critical steps that remain to be addressed before these therapies can be used in patients are also discussed. Key milestones include the harvesting of neural stem cells from the human gut and the latest in vivo transplantation studies in animals. The tremendous progress in the field has brought experimental studies exploring the potential of stem cell therapies for the management of enteric neuropathies to the cusp of clinical application.