Possible Effects of Mesenchymal Stem Cells on Submandibular and Sublingual Salivary Glands of Streptozotocin Induced Diabetic Albino Rats (histological and immunohistochemical study)

Abstract

Considering the severe impact of diabetes may have on patients’ quality of life, there is a need for an efficient treatment. The aim of this research was to suggest an updated description of Mesenchymal Stem Cells possible effects on Submandibular and Sublingual Salivary Glands of Streptozotocin induced Diabetic albino rats. Materials and Methods: The forty adult male rats were randomly and equally divided into four groups where n=10 as follows: Group I (Control group): Rats received intravenous injection of 1ml/kg sodium citrate buffer (STZ solvent) and were considered control group for STZ induced diabetic group. Group II (Control group): Rats received intravenous injection of 1ml/kg sodium citrate buffer together with intravenous injection of phosphate buffer saline (MSCs solvent) and were considered control group for MSCs treated diabetic group. Group III (STZ induced diabetic group): This group was assigned for development of diabetes. Diabetes was induced by a single intravenous injection of STZ (Sigma-Aldrich Co.) with a dose of (55 mg/kg). STZ was freshly prepared by dissolving it in 0.1 M citrate buffer (pH 4.5, Sigma-Aldrich Co.) and immediately injected into the tail vein after 8 hours of fasting. After one week, fasting blood glucose levels were measured and rats with blood glucose levels >200 mg/dL were considered diabetic. Group IV (MSCs treated diabetic group): Rats of this group were injected intravenously with prepared MSCs 1x106/rat after diabetes induction as the previous group. The sections of rats’ salivary glands were processed and stained by Haematoxylin and Eosin for the histological study and immunohistochemical staining for Caspase 3 localization was done. Unstained glass slides were examined with a fluorescence microscope in order to detect the stained cells with PKH26 dye to ensure homing of MSCs to salivary glands. Results: Histological Results: The current study revealed that several histological changes occurred in both SMG & SLG of STZ induced diabetic group. The SMG demonstrated loss of the normal gland architecture. This was manifested by the appearance of ill defined acinar cell borders together with an overall increase in cytoplasmic basophilia of the acini. Most of acinar cells nuclei appeared deeply stained pyknotic with perinuclear spacing. Different sized cytoplasmic vacuolations were seen in the acinar cells cytoplasm and were aggravated in cells lining the GCTs. Few GCT cells showed deeply stained basophilic pykontic nuclei. Some lining cells showed disruption of the continuity of their epithelial lining leading to leaching of eosinophilic granules found in cell apices. In some specimens, some areas showed acinar degeneration manifested by the appearance of wide spaces with few remnants between the acini, while other serous acini demonstrated mucous transformation The SLG showed some variation in size. Some acini appeared to be reduced in size, while others appeared same size as those of the control groups. The acini borders appeared thickened. The mucous acinar cytoplasm lost their foamy appearance and showed an increase in basophilia. Most of the cells nuclei appeared deeply stained. In some areas, signs of acinar degeneration were found. In this study, the striated ducts of SMG and SLG of the same group showed complete loss of basal striations with marked pyknosis of ductal nuclei. While, the excretory ducts of both salivary glands showed loss of usual pseudostratified appearance. The epithelium showed focal degeneration. The lumen appeared dilated with noticeable desquamated cells nuclei and pink stained secretion. Neighboring B.Vs were obviously dilated and engorged with R.B.Cs. In the present study, examination of salivary glands of MSCs treated diabetic albino rats revealed that both glands generally exhibited normal architecture, having morphological outline and staining similar to those of the control groups. The serous acini of SMG appeared with pale basophilic granular cytoplasm and basal rounded nuclei. Intra-acinar cytoplasmic vacuolations were occasionally found. Most of GCTs appeared normal with regular granular content and basally situated rounded nuclei and eosinophilic cytoplasm with minimal vacuolations. The cytoplasm in the apical region of the mucous cells of SLG was noticed foamy and faintly basophilic in appearance. The nuclei of the mucous cells appeared angular or flattened and located mostly at the basal end of the cells.