The expression and localization of osteopontin in the mouse major salivary glands

Effects of bovine milk osteopontin on in vitro enamel remineralization as a topical application prior to immersion in remineralizing solutions with/without fluoride

The aim of the present study was to investigate the effects of bovine milk osteopontin (OPN) on enamel remineralization as a topical application prior to immersion in remineralizing solutions with/without fluoride. Bovine enamel blocks were demineralized then were divided into the following 3 groups: OPN (2.7 and 5.4 µM) solutions and deionized water (control). Each group was divided into 2 groups (remineralizing solution with or without 1 ppm of fluoride (F)). The specimens were analyzed by micro-CT and scanning electron microscope (SEM). The percentage of remineralization was higher in remineralization solution with than without F (p<0.05). The present results suggest that bovine milk OPN inhibits remineralization in solution without F, but 5.4 µM bovine milk OPN does not inhibit remineralization of the demineralized body using solution containing F by interrupting mineral deposition on the enamel surface.

Salivary Osteopontin as a Potential Biomarker for Oral Mucositis

Osteopontin (OPN), a multifunctional phosphoglycoprotein also presents in saliva, plays a crucial role in tumour progression, inflammation and mucosal protection. Mucosal barrier injury due to high-dose conditioning regimen administered during autologous and allogeneic peripheral stem cell transplantation (APSCT) has neither efficient therapy nor established biomarkers. Our aim was to assess the biomarker role of OPN during APSCT, with primary focus on oral mucositis (OM). Serum and salivary OPN levels were determined by ELISA in 10 patients during APSCT at four stages of transplantation (day -3/-7, 0, +7, +14), and in 23 respective healthy controls. Results: There was a negative correlation between both salivary and serum OPN levels and grade of OM severity during APSCT (r = -0.791, p = 0.019; r = -0.973, p = 0.001). Salivary OPN increased at days +7 (p = 0.011) and +14 (p = 0.034) compared to controls. Among patients, it was higher at day +14 compared to the time of admission (day -3/-7) (p = 0.039) and transplantation (day 0) (p = 0.011). Serum OPN remained elevated at all four stages of transplantation compared to controls (p = 0.013, p = 0.02, p = 0.011, p = 0.028). During APSCT elevated salivary OPN is a potential non-invasive biomarker of oral mucositis whereas the importance of high serum OPN warrants further studies.

Expression and localization of osteopontin, homing cell adhesion molecule/CD44, and integrin αvβ3 in pleomorphic adenoma, polymorphous low-grade adenocarcinoma, and adenoid cystic carcinoma

OBJECTIVES

Osteopontin (OPN) plays a role in tumor progression. This study aimed to determine the expression of OPN, CD44, and integrin αvβ3 in pleomorphic adenoma (PA), polymorphous low-grade adenocarcinoma (PLGA), and adenoid cystic carcinoma (ACC).

STUDY DESIGN

Immunohistochemistry was used to semiquantify the level of expression of OPN and its receptors in normal salivary glands (NSG; n = 20), PA (n = 20), PLGA (n = 16), and ACC (n = 22).

RESULTS

OPN expression was increased in PLGA and intermediate-/high-grade ACC compared with PA and NSG (median scores, 6, 5, 4, and 4, respectively). CD44 expression was reduced in PA, PLGA, and ACC. OPN expression levels were moderately correlated with CD44 in PLGA. Integrin αvβ3 was not expressed in PA and ACC and was seen in only 1 case of PLGA.

CONCLUSIONS

OPN is expressed in salivary gland tumors but does not correlate well with CD44 and αvβ3.

Expression and localization of osteopontin, homing cell adhesion molecule/CD44, and integrin αvβ3 in mucoepidermoid carcinoma and acinic cell adenocarcinoma of salivary gland origin

OBJECTIVE

Osteopontin (OPN) plays a role in tumor progression. This study aimed to determine the expression of OPN, CD44, and integrin αvβ3 in pleomorphic adenoma (PA), acinic cell adenocarcinoma (ACA), and mucoepidermoid carcinoma (MEC).

STUDY DESIGN

Immunohistochemistry was used to semiquantify the levels of expression of OPN and its receptors in normal salivary glands (NSG) (n = 20), PA (n = 20), ACA (n = 11), and MEC (n = 29).

RESULTS

OPN expression was increased in ACA and MEC compared with PA and NSG (median scores, 6, 6, 4, and 4, respectively). CD44 expression was increased in ACA and reduced in MEC and PA compared with NSG (median scores, 8, 4, 3, and 5, respectively). Integrin αvβ3 median scores were 5 in ACA, 1 in MEC, and 0 in PA and NSG.

CONCLUSIONS

OPN is expressed in salivary gland tumors and is at higher levels in ACA and MEC.

Human salivary gland stem cells: isolation, propagation, and characterization

Stem cells are of outstanding interest for a variety of applications in regenerative medicine. The identification and characterization of novel tissue sources in order to reduce donor site morbidity and to provide specific cells in clinically applicable numbers have led to the detection of stem cells in almost all adult tissues. Salivary glands are of specific interest to our lab, as these tissues are easily accessible for the head and neck surgeon with low donor site morbidity. On the other hand, they possess an endocrine and exocrine function and thus play a very specific role in the human body. Stem cell identity however can only be demonstrated using a combination of different methods in vitro, as there is not a single marker or feature allowing for definite identification of such cells. In this chapter, we provide a comprehensive summary of our experimental methods for the isolation and characterization of human salivary gland stem cells in vitro.

Isolation and characterization of adult stem cells from human salivary glands

Currently, adult stem cells are attracting significant interest in regenerative medicine and tissue engineering. These cells have been isolated from various tissue sources; however, in most cases, adult stem cells useful for tissue engineering and regeneration are present at a low frequency. High numbers of stem cells with an effective and reliable potential for differentiation are needed for clinical applications. Thus, the identification of new stem cell sources and the establishment of optimized cell culture conditions that allow for the amplification of stem cells are of utmost relevance. In addition, the isolation procedure should ideally be minimally invasive and possibly be performed under local anesthesia. We report here for the first time on the identification of adult stem cells with mesenchymal characteristics in human parotid gland tissue. Cells were isolated from freshly resected specimens of parotid glands using enzymatic digestion and plastic adhesion protocols. Following an initial proliferation period and short-term culture for four passages, immunophenotyping revealed the presence of mesenchymal stem cell markers. In the presence of tissue-specificinduction medium, stem cells could be differentiated into adipogenic, osteogenic, and chondrogenic cell types. Tissue-specific differentiation was confirmed by histochemical and immunocytochemical staining as well as by RT-PCR for defined marker genes. This study is, to the best of our knowledge, the first report on the isolation and differentiation of stem cells from adult human parotid glands. Although isolated from an endodermal tissue source, these stem cells share many characteristics with MSCs. Easy accessibility and a high differentiation potential make salivary gland-derived stem cells a promising source for future applications in regenerative medicine.