Oral Progenitor Cells Suppress T-cell Proliferation Via Induction of Anergy

In addition to tissue engineering applications, emerging evidence suggests that some mesenchymal stem cells (MSC) may be useful in the treatment of inflammatory diseases due to their immunosuppressive properties. We have previously demonstrated the potent immunosuppressive properties of oral mucosal lamina propria progenitor cells (OMLP-PCs). This study aims to determine the direct effect of OMLP-PCs on T cell proliferation and their potential for use in the treatment of immune-related disorders.

Methods:

CD3+ T cells were purified from buffy coats by MACS® separation, activated (anti-CD2/CD3/CD28 beads) and co-cultured in contact and transwell systems with OMLP-PCs for 5 days.  Flow cytometry was used to determine T cell activation and proliferation by CD25 and CFSE labelling respectively.  T cell viability and apoptosis was determined by trypan blue exclusion and dual cell labelling with Live/Dead® cell stain and annexin V and detected by flow cytometry.  T cell anergy was assessed using phytohaemagglutinin-M (PHA-M) stimulation after removal of the OMLP-PCs (n=3).

Results:

Flow cytometry confirmed a decrease in T cell division coupled with a decrease in the level of CD4+CD25+ and CD8+CD25+ activated T cells. Annexin V staining confirmed that OMLP-PCs directly inhibit T cell proliferation whilst protecting the T cells against apoptosis (P≤0.05). Inhibition of T cell proliferation by OMLP-PCs was not reversible by their removal and re-stimulation with the T cell mitogen PHA-M suggesting induction of T cell anergy (P≤0.05).

Conclusions:

This study demonstrates the potent immunosuppressive capabilities of OMLP-PCs on T cell proliferation in vitro. We have determined that OMLP-PCs modulate both T helper and cytotoxic T cell proliferation through the induction of anergy but without adversely affecting their viability. Investigations are now focussed on determining the specific mechanism involved in mediating these effects. 

Funding from the MRC (G0901562), NISCHR (HA09-034) is gratefully acknowledged. This work is subject to patent filing.