Diabetes Mellitus (DM), a chronic disorder, requires a long-term remedy to control glucose in the blood, as both hyperglycemia and hypoglycemia prompt severe health issues. DM affect about 390 million people worldwide and the number is expected to grow up by 500 million by 2030 [19]. An alloxan induced diabetic mice model was developed to mimic the human pathogenesis of DM by a single intraperitoneal dose [20] and PRP treatment was employed to diabetic mice. Several studies have suggested the antidiabetic potential and glycemic control capability of PRP in animals [21]. Previous studies revealed the ability of autologous PRP to recover insulin secretion of pancreatic islets as well as to improve oxidative stress and regulation of insulin and glucose levels in plasma in diabetic rats [22]. Current study was therefore conceded to highlight the therapeutic outcome of heterologous platelet-rich plasma (PRP) on diabetic liver injury by regulating glucose metabolism in a mice model of T2DM.
Analysis of blood revealed a higher level of glucose and C-peptide in diabetic group and PRP treatment reversed the effect significantly in T2G but it was insignificant in T1G (Fig. 1a,b). C- Peptide, as a result of pro-insulin cleavage, is produced in equimolar concentration to insulin and it is used to detect endogenous insulin secretion by β-cells of pancreatic islets as elevated level of C-Peptide in hyperglycaemia indicates an inappropriately low level of insulin and consequent higher glucose in blood.
Histochemical analysis revealed a noteworthy increase in collagen protein in alloxan-induced diabetic mice (Fig. 2b). Hepatic fibrosis, the increased deposition of extracellular matrix (ECM) protein, is a major cause of chronic liver injury [23] and T2DM potentiates liver inflammation and ultimate severe liver failure in addition to the prevalence of bacterial infections [24]. The inflammation along with oxidative stress causes chronic hyperglycemic injuries and lipid disorder in hepatic tissues [25]. Persistent hepatic fibrosis can lead to liver cirrhosis and ultimately to organ failure and death.
Moreover, ballooning of hepatocytes, infiltration of inflammatory cells and deposition of fat globules with damaged sinusoidal spaces (Fig. 2a) was also observed in DG which is consistent with the previous studies [19] and it was significantly reduced in both the treated groups T1G and T2G. PRP may ameliorate hepatic microarchetecture and reduce the accumulation of ECM and inflammation in hepatic tissues by moderating the activation of hepatic stellate cells (HSCs) as they have a critical role in hepatic fibrogenesis [26].
The liver, as a central organ, is a key player of glucose homeostasis. To deepen the role of the liver in glucose homeostasis, some indicators of glucose metabolism and the Wnt signaling pathway, connected to impaired homeostasis of glucose in T2DM, were also investigated in current study. The expression of some key gluconeogenesis genes, Fbp1, G6pc, and Pklr, was upregulated which is consistent with the previous reports but we found reduced expression of Pck, another gluconeogenesis gene, in DG compared to CG that contradict the previous studies [27]. The increased expression of Fbp1, Pklr, and G6pc perceived in the current study is associated with the fact that mice liver might be able to boost the rate of gluconeogenesis at a relatively earlier stage of diabetes to elevate glucose level in diabetic mice.
In the glycolytic pathway, it is reported that the activity of both Hk1 and Gck is decreased in the diabetic liver which is in line with the previous study [28, 29]. The decreased expression of Hk1 and Gck detected in the current study is also connected to the fact that mouse liver might be able to downregulate glycolysis to elevate glucose level in diabetic mice. Taken together, our data implicate that downregulation of glycolysis to decrease consumption of glucose and upregulation of gluconeogenesis were augmented to yield higher glucose level (Fig. 1a). Increased gluconeogenesis accounted for about 90% elevation in hepatic glucose production and the remaining about 10% rise is probably contributed by slightly elevated glycogenolysis in T2DM subjects [14]. PRP treatment restore the expression of Fbp1and G6pc, which was increased in DM, to nondiabetic level but no significant restoration in expression of Pklr was observed. Pck1 expression tended to decrease in DM, and PRP therapy reversed the effect. Moreover, the expression of Hk1 and Gck is also observed to be restored after the treatment of PRP.
The current study also showed an increased expression of Wnt2, Wnt4, and Wnt9a genes in DG as compared to CG, and a noteworthy reduction in expression was observed in both T1G and T2G. DG showed no significant change in expression of Wnt5b and Wnt9b as compared to CG (Fig. 3). The Wnt signaling pathway is critically important to modulate the differentiation of adipocytes [30]. Wnt2, Wnt4, and Wnt5b have been studied previously and an escalation in expression was observed in experimentally induced T2DM [31] but no direct evidence is available for the link of Wnt9a and Wnt9b to T2DM. Expression of Wnt genes in preadipocytes inhibit the canonical Wnt signaling and increase adipogenesis and expression of adipokine genes. The adipokines, synthesized and secreted by adipocytes, were thought to be intricate in systemic insulin sensitivity. Thus, adipogenesis could be altered by the change in Wnt gene expression and, consequently, it affects the risk of the onset of diabetes.
Taken together, the findings of the current study provide new insights to the control of hepatic glucose metabolism and the development of T2DM and revealed that the heterologous PRP anticipates a reduction in hepatic glucose production as well as glucose consumption. So, it may use as one of the adjunctive therapies to treat T2DM in the future but further studies are warranted.