Abstract
Introduction: Dental pulp stem cells (DPSCs) express naturally high positivity for surface receptor glycoprotein CD 44 which is involved in the induction of odontoblast mineralization with hyaluronic acid (HA) being its major ligand. The aim of this experiment was to assess the effect of HA in low (LMW-HA), medium (MMW-HA) and high (HMW-HA) molecular weights on the phenotypic profile, proliferation activity and differentiation potential of human DPSCs.
Methods: The experiment was conducted in vitro on two lines of human DPSCs from different donors (third molar - male, 25 years and first premolar - male, 9 years). These lines were cultured in standard medium and from the second passage also in three experimental culture media containing 0.1% HA in three molecular weights: LMW-HA (116 kDa), MMW-HA (540 kDa) and HMW-HA (1500 kDa).
The phenotypic analysis was performed in the seventh passage using a Vi-Cell XR flow cytometer, viability was evaluated by the Vi-Cell Analyzer in the seventh passage and proliferation activity measured by the Z2 Counter Analyzer in every passage. Osteo- and chondrodifferentiation were inducted by commercially supplied cultivation media and demonstrated by histological staining with alcian blue and alizarin red.
Results: DPSCs used in our experiment expressed phenotype typical for human DPSCs (high positivity for CD 13, CD 29, CD 44, CD 90 and OCT 3/4), they were able to exceed Hayflick limit and differentiate in the osteogenic as well as the chondrogenic extracellular matrix. During the experiment, DPSCs line 1 cultivated in control medium / medium 1 (116 kDa HA) / medium 2 (540 kDa HA) / medium 3 (1500 kDa HA) achieved in this order in total 14.1/15.3/15.4/14.8 population doublings.
The median of doubling time with the minimal and maximal values in the same order was 31.6 (29.2; 36.8) / 29.6 (28.5; 30.6) / 30.3 (26.7; 31.3) / 30.5 (29.7; 33.8) hours. The viability of the DPSCs obtained from the seventh passage was in the same order 92.3/93.1/91.8/92.6%.
DPSC line 2 cultivated in control medium / medium 1 (116 kDa HA) / medium 2 (540 kDa HA) / medium 3 (1500 kDa HA) achieved in this order in total 16.7/17.2/16.7/16.8 population doublings. The median of doubling time with the minimal and maximal values in the same order was 28.9 (24.5; 35.2) / 27.4 (24.5; 32.6) / 28.3 (24.0; 38.4) / 27.1 (25.3; 33.9) hours.
The viability of the DPSCs obtained from the seventh passage was in the same order 80.1/82.5/81.8/80.9%. Conclusion: We verified that DPSCs in the presence of hyaluronic acid at a concentration of 0.1% and molecular weights of 116, 540 and 1500 kDa survive, proliferate and maintain the ability to differentiate in mature cellular elements.
We also verified the original assumption that the low molecular weight form of hyaluronic acid has a different impact on the DPSCs' phenotype than the high molecular weight form of hyaluronic acid.