Gingiva and Alveolar Bone Proper-derived Stem Cells’ TLR Expression

Objectives: Dental tissue derived stem/progenitor cells (MSCs) isolated via minimally invasive procedures have gained steadily in importance in the field of regenerative medicine. Previous studies showed distinctive toll-like receptors (TLRs) expression profiles for MSCs from different tissue sources, possibly affecting their interaction potential with their surrounding environment during regenerative procedures. The present study aimed to characterize and compare for the first time the TLRs’ expression profiles of gingival and alveolar bone proper derived MSCs (G-MSCs and AB-MSCs respectively).
Methods: Cells were isolated from the free gingival margin and alveolar bone proper (n=5), immunomagnetically sorted using anti-STRO-1 antibodies, to be finally seeded and expanded in basic medium to obtain single colony forming units (CFUs). After 12 days single colonies of G-MSCs and AB-MSCs were isolated and expanded. G-MSCs and AB-MSCs were characterized for the expression of CD14, CD34, CD45, CD73, CD90, CD105, CD146 and STRO-1 by flow-cytometry and for their multilineage differentiation potential. Subsequently, the expression of the TLRs 1-10 was investigated for both types of MSCs by flow-cytometry.

Results: G-MSCs and AB-MSCs showed all predefined stem/progenitor cells’ characteristics. G-MSCs expressed (Median Percentage, Q25/Q75) TLR1 (31.37, 27.75/44.96), TLR2 (51.04, 34.02/69.57), TLR3 (2.22, 1.02/16.01), TLR4 (41.67, 40.32/48.70), TLR5 (42.20, 39.14/52.28), TLR7 (4.68, 0.73/25.18),TLR8 (1.68, 0.6/9.04), TLR9 (2.75, 1.15/10.08) and TLR10 (56.47, 34.14/71.59).
AB-MSCs expressed (Median Percentage, Q25/Q75) TLR1 (15.12, 11.37/21.23), TLR2 (43.62, 40.21/49.52), TLR3 (1.67, -1.04/1.98), TLR4 (32.15, 25.31/45.67), TLR5 (30.93, 26.39/35.71), TLR6 (3.34, -2.61/7.35), TLR7 (38.54, 15.09/47.50), TLR8 (9.52, 1.08/14.36) and TLR10 (13.67, 9.43/58.48). G-MSCs showed statistically higher TLR1 (p=0.008; Mann-Whitney-U test) and TLR5 (p=0.008; Mann-Whitney-U test) expression compared to AB-MSCs.
Conclusions: G-MSCs and AB-MSCs show distinctive TLR expression profiles. TLRs 1 and 5 were higher expressed in G-MSCs. The expressed TLRs may have an important impact on the cells’ interaction with their inflammatory surrounding during regeneration processes in vivo.