Associate Professor Duke University, North Carolina, United States
Background/Case Studies: The blood–brain barrier (BBB) is a specialized structure that protects the central nervous system (CNS) by regulating the infiltration of immune cells and blood-borne molecules. During neuroinflammatory diseases such as multiple sclerosis (MS) or its animal model, experimental autoimmune encephalomyelitis (EAE), increased permeability due to reduced barrier integrity allows circulating immune cells to infiltrate CNS tissue. As a multicellular structure, the integrity of the BBB barrier is supported by various cell types, including microvascular endothelial cells (MECs), pericytes, perivascular macrophages, and astrocyte endfeet. Given that endogenous CNS macrophages play a role in regulating BBB barrier function, macrophages derived from banked human umbilical cord blood were tested to provide protective effects in the context of EAE.
Study
Design/Methods: The EAE model was used to assess whether cord-blood derived macrophages (referred to as DUOC-01 in a clinical trial for primary progressive MS (NCT04943289)) can suppress the progression of neuroinflammatory disease by restoring the integrity of the BBB. EAE was induced in C57BL/6 mice by immunization with myelin oligodendrocyte glycoprotein peptide (MOG₃₅–₅₅) emulsified in complete Freund’s adjuvant. To generate DUOC-01, mononuclear cells isolated from human umbilical cord blood were treated with insulin-transferrin-selenium, PDGF, VEGF, NT3, and T3 for 14 days, followed by culture in PDGF, VEGF, and NT3 for an additional 7 days. DUOC-01 were injected into the cerebrospinal fluid at the onset of EAE symptoms. MEC activation was measured by flow cytometry, multiplex immunoassay, immunohistochemistry, and transwell migration assays.
Results/Findings: DUOC-01 halted the progression of clinical disease whereas there were no effects of macrophages derived from adult blood monocytes. Additionally, DUOC-01 reduced the infiltration of myeloid cells into the spinal cord and suppressed the expression of chemokines induced by EAE. DUOC-01 rescued the integrity of the BBB by restoring the expression of tight junction proteins in MECs and preventing fibrinogen extravasation into the spinal cord. To assess the direct effects of DUOC-01 on MECs, an in vitro culture system was established using MECs isolated from mouse brain. In this system, DUOC-01–MEC interactions reduced chemokine release from MECs and attenuated the trans-endothelial layer migration of leukocytes isolated from peripheral blood. Apoptotic DUOC-01, generated by staurosporine treatment, retained bioactivity both in vivo and in vitro, although their efficacy was slightly reduced compared to that of live DUOC-01.
Conclusions: This study revealed a direct interaction between DUOC-01 and MECs that reduced damage in EAE by restoring BBB integrity and function. This supports further development of DUOC-01 as a novel cell therapy to suppress neuroinflammation.
