Oral Mucosal Lamina Propria Progenitor Cell Modulation of Lymphocyte Proliferation

Objectives: We have previously demonstrated that a progenitor cell (PC) population resides within the human oral mucosal lamina propria (OMLP) that is capable of generating cells of mesenchymal and neuronal lineages. Emerging evidence suggests that mesenchymal stem cells (MSC) may be useful in the treatment of inflammatory diseases due to their immunosuppressive properties. This study aimed to determine the immunological properties of OMLP-PCs and their potential for use in allogeneic tissue engineering and in the treatment of immune-related disorders.

Methods: Clonal populations of human OMLP-PCs (n=3) were expanded in monolayer culture. All assays were carried out +/- 100U/ml Interferon γ (IFNγ). Expression of Human Leukocyte Antigen (HLA) classes I and II on the cell surface and intracellularly were determined by FACS and Western Blotting. Mixed lymphocyte cultures (MLC) were performed +/- the T cell mitogen phytohaemagluttinin in contact and transwell systems. Data was statistically analysed by ANOVA and a Bonferroni Post-hoc test.

Results: HLA I was constitutively expressed on the cell surface of OMLP-PCs. Intracellular expression of HLA II was inducible after 24 hours of treatment with IFNγ however, cell surface expression was not detectable until day 7 of IFNγ treatment. MLCs confirmed that OMLP-PCs potently suppress lymphocyte proliferation in vitro in a concentration and contact independent manner (P<0.001 compared to controls) and that the mechanism of immunosuppression was HLA II independent.

Conclusion: This study demonstrates the potent immunosuppressive capacity of OMLP-PCs.OMLP-PCs significantly suppress lymphocyte proliferation in a concentration and contact independent manner, suggesting that these cells may be ideal candidates for allogeneic tissue engineering. These data also demonstrate the enhanced potential of OMLP-PCs for use in the treatment of immune-related disorders over MSCs that are currently being utilised.

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