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In vitro replication and differentiation of normal human oral keratinocytes
1Dental Research Institute, School of Dentistry, School of Medicine, Jonsson Comprehensive Cancer Center, University of California, Center for Health Sciences, 10833 Le Conte Avenue, Los Angeles, California 90095-1668, USA.
Experimental Cell Research
|July 18, 2000
Summary
Normal human oral keratinocytes (NHOK) exhibit distinct replication phases, with senescence preceding terminal differentiation. Differentiation can be induced independently of replication arrest in these cells.
Area of Science:
- Cell Biology
- Dermatology
- Oral Biology
Background:
- Normal human oral keratinocytes (NHOK) are crucial for oral tissue maintenance and repair.
- Understanding NHOK replication and differentiation is vital for regenerative medicine and understanding oral diseases.
Purpose of the Study:
- To analyze the replication kinetics and cytological changes of normal human oral keratinocytes (NHOK) in vitro.
- To investigate the relationship between replication arrest and terminal differentiation in NHOK.
Main Methods:
- NHOK were cultured in low calcium medium and analyzed for replication using cell counts and [3H]thymidine uptake.
- Cell morphology, beta-galactosidase (beta-gal) activity, involucrin, and cytokeratin (K1/K10) expression were assessed via microscopy and cytochemical staining.
- NHOK were treated with 5-aza-2'-deoxycytidine (5-aza CdR) or high calcium (1.5 mM Ca2+) to study differentiation induction.
Main Results:
- NHOK displayed three replication phases: exponential, senescing, and senescent, independent of donor age.
- Replication arrest coincided with increased beta-gal staining, indicating senescence.
- Terminal differentiation (K1/K10 expression) occurred after replication arrest and maximal beta-gal staining.
- 5-aza CdR induced differentiation after inhibiting DNA replication, while high calcium induced differentiation without inhibiting replication.
Conclusions:
- Replication arrest precedes terminal differentiation in serially subcultured NHOK.
- Terminal differentiation in NHOK can be induced independently of replication arrest.