T cell immunomodulation by clinically used allogeneic human cancellous bone fragments: a potential novel immunotherapy tool

Yasser M El-Sherbiny,Dennis Mcgonagle,Elena Jones,Jehan J El-Jawhari,Timothy A Moseley

doi:10.1038/s41598-018-31979-1

Abstract

Multipotential stromal cells (MSCs) demonstrate strong immunomodulation capabilities following culture expansion. We have previously demonstrated that human cancellous bone fragments (CBFs) clinically used as viable allografts for spinal fusion have resident MSCs that exhibit T cell immunomodulation after monolayer expansion. This study investigated the immunomodulatory ability of these CBFs without MSC culture-expansion. CD4 positive T cells were induced to proliferate using CD3/CD28 stimulation and added to CBFs at different ratios of T cells per gram of CBF. A dose-dependent suppressive effect on T cell proliferation was evident and correlated with increased culture supernatant levels of TGF-ß1, but not PGE2. CBF-driven immunosuppression was reduced in co-cultures with TGF-ß neutralising antibodies and was higher in cell contact compared to non-contact cultures. CBF gene expression profile identified vascular cell adhesion molecule-1, bone marrow stromal antigen 2/CD317 and other interferon signalling pathway members as potential immunomodulatory mediators. The CD317 molecule was detected on the surface of CBF-resident cells confirming the gene expression data. Taken together, these data demonstrate that human clinically used CBFs are inherently immunomodulatory and suggest that these viable allografts may be used to deliver therapeutic immunomodulation for immune-related diseases.

Highlights

In the last decade, cellular therapy such as multipotential stromal cells (MSCs) has been used extensively for immunomodulation in the variety of clinical settings including graft-versus-host disease (GVHD), Crohn’s disease, rheumatoid arthritis, kidney transplantation, type II diabetes and multiple sclerosis with promising outcomes[1,2,3]
We have previously shown that human cancellous bone fragments (CBFs) clinically-used as cellular bone allografts to augment bone regeneration primarily for spine fusion, contain bone-resident Multipotential stromal cells (MSCs) capable
Gene expression analysis of CBFs prior to co-cultures provided a list of candidate immunomodulatory molecules potentially eliciting immunomodulation, with CD317 being confirmed at the protein level

Summary

Introduction

Cellular therapy such as multipotential stromal cells (MSCs) has been used extensively for immunomodulation in the variety of clinical settings including graft-versus-host disease (GVHD), Crohn’s disease, rheumatoid arthritis, kidney transplantation, type II diabetes and multiple sclerosis with promising outcomes[1,2,3]. Monolayer expansion) of the suppression of stimulated CD4+ T-cell proliferation, in addition to their classical MSC tri-lineage differentiation abilities[11]. These CBFs are produced from cadaveric human cancellous bone using extensive immuno-depletion bone washing procedures and are histologically characterised by an almost complete removal of blood-lineage cells from the bone marrow cavity. We hypothesised that these CBFs could have an innate immunomodulatory activity partially related to MSC content In support of this hypothesis, immunosuppressive effects of allogeneic bone grafts have been previously reported in several independent animal studies[15,16,17]. These findings suggest that these CBFs may potentially be used to elicit therapeutic immunomodulation in the clinical settings

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