ABSTRACT
BACKGROUND: Recently, we showed that transplantation of 100-300 c-Kit(+) stem cells isolated from cultured salispheres ameliorates radiation-damage in murine salivary glands. The aim of this study is to optimize and translate these findings from mice to man. METHODS: Mouse and human non-malignant parotid and submandibular salivary gland tissue was collected and enzymatically digested. The remaining cell suspension was cultured according to our salisphere culture method optimized for murine salispheres. Salisphere cells were tested using 3D matrix culturing for their in vitro stem cell characteristics such as the potential to differentiate into tissue specific cell types. Several potential mouse and human salivary gland stem cells were selected using FACS. RESULTS: In human salivary gland, c-Kit(+) cells were only detected in excretory ducts as shown previously in mice. From both human parotid and submandibular gland cell suspensions salispheres could be grown, which when placed in 3D culture developed ductal structures and mucin-expressing acinar-like cells. Moreover, cells dispersed from primary salispheres were able to form secondary spheres in matrigel, a procedure that could be repeated for at least seven passages. Approximately 3000 c-Kit+ cells could be isolated from primary human salispheres per biopsy. CONCLUSION: Human salivary glands contain a similar 'putative' stem cell population as rodents, expressing c-kit and capable of in vitro differentiation and self-renewal. In the future, these cells may have the potential to reduce radiotherapy-induced salivary gland dysfunction in patients.
Subject(s)
Radiation Injuries/prevention & control , Salivary Glands/radiation effects , Stem Cell Transplantation/methods , Xerostomia/prevention & control , Animals , Cells, Cultured/radiation effects , Disease Models, Animal , Female , Flow Cytometry , Humans , Immunohistochemistry , Mice , Mice, Inbred C57BL , Probability , Proto-Oncogene Proteins c-kit/metabolism , Radiation, Ionizing , Random Allocation , Recovery of Function , Regeneration/physiology , Salivary Gland Diseases/radiotherapy , Salivary Gland Diseases/surgery , Salivary Glands/cytology , Salivary Glands/pathology , Statistics, NonparametricABSTRACT
Hyposalivation induced by exposure of the salivary gland to radiation while treating head and neck cancer patients, can result in xerostomia (dry mouth syndrome), which burdens the patient with oral dryness or pain, dental caries, reduced taste and smell, increased risk for oral infections, hampered speech, and problems with food mastication. Stem cell therapy may be an option to reduce radiation-induced damage to the salivary glands permanently. This Directions in Science article reviews a recent study (Lombaert et al, 2008) using tissue stem cells to regenerate the salivary glands from cells that originate from putative stem cells residing in the ductal compartment. Lombaert et al showed restoration of function of irreversibly damaged mouse submandibular glands after intraglandular injection of an in vitro cultured c-Kit+ cell population containing salivary gland stem cells. The findings raise the prospect of clinical autologous salivary gland stem cell transplantation after radiotherapy.
Subject(s)
Stem Cell Transplantation , Submandibular Gland/physiology , Submandibular Gland/radiation effects , Animals , Mice , RegenerationABSTRACT
Titanium alloy material (TC4) samples were treated with nitriding technique. The dynamic friction and wear behavior of the modified layer were examined on a reciprocating sliding rig in artificial saliva. Microhardness, depth profile and wear mechanisms were investigated by means of MVK-H12, TALYSURF6, XPS and microscopy. The results demonstrate that after being treated with nitriding technique the titanium alloy material (TC4) has better tribological behavior and up-graded wear resistance. The wear mechanism involves adhesion.
Subject(s)
Dental Prosthesis , Materials Testing , Titanium/chemistry , Adsorption , Biocompatible Materials , Dental Alloys/chemistry , Dental Materials , Electricity , Friction , Humans , Surface PropertiesABSTRACT
OBJECTIVE: This study aimed at investigating bio-tribological property of titanium opposite to teeth as a base of clinical application. METHODS: Under a modified fretting machine, wear tests on human natural teeth were carried out in artificial saliva conditions against to pure titanium. The dynamic frictional process and wear mechanisms were investigated by means of Nene-2, MVK-H12, TALYSURF6, OM, LSM, SEM, EDX. RESULTS: The coefficient of friction exhibited a variation pattern of longs. The wear mechanism of natural tooth was detected as micro-cut and denaturation of dental texture and the wear depth of Ti/teeth was 20.33 + 2.86 microm, the wear depth of Ti/Ti being 38.00 + 5.88 microm (P < 0.05). CONCLUSIONS: The natural tooth has a good tribological behavior, matching the friction behavior of pure titanium. Over occlusal force during masticate process and para-function should be avoided. When we chose dental materials, wear resistance should be taken into account.
