Periodontal ligament (PDL) repair is thought to involve mesenchymal progenitor cells capable of forming fibroblasts, osteoblasts and cementoblasts.
However, full characterization of PDL stem cell (SC) populations has not been achieved.
A group of scientists isolated and characterized PDLSC and assessed their capability to differentiate into bone, cartilage and adipose tissue.
For this purpose they have taken Human PDL cells stained them for STRO-1, FACS sorted and expanded in culture.
Human bone marrow SC (BMSC) served as a positive control.
PDLSC and BMSC were cultured using standard conditions conducive for osteogenic, chondrogenic and adipogenic differentiation.
Osteogenic induction was assayed using alizarine red S staining and expression of alkaline phosphatase (ALP) and bone sialoprotein (BSP).
Adipogenic induction was assayed using Oil Red O staining and the expression of PPAR gamma 2 (early) and LPL (late) adipogenic markers.
Chondrogenic induction was assayed by collagen type II expression and toluidine blue staining.
During these experiments they found that human PDL tissue contains about 27% STRO-1 positive cells with 3% strongly positive.
In osteogenic cultures ALP was observed by day-7 in BMSC and day-14 in PDLSC.
BSP expression was detectable by day-7; with more intense staining in PDLSC cultures.
In adipogenic cultures both cell populations showed positive Oil Red O staining by day-25 with PPAR gamma 2 and LPL expression.
By day-21, both BMSC and PDLSC chondrogenic induced cultures expressed collagen type II and glycosaminoglycans.
So it can be stated that the PDL contains SC that have the potential to differentiate into osteoblasts, chondrocytes and adipocytes, comparable with previously characterized BMSC.
This adult PDLSC population can be utilized for potential therapeutic procedures related to PDL regeneration.