Ph.D Thesis


Ph.D StudentBeckerman Margarita
SubjectEngineered Muscle Tissue for Restoring Insulin Sensitivity
in Type 2 Diabetes Patients
DepartmentDepartment of Biomedical Engineering
Supervisors PROF. Shulamit Levenberg
PROFESSOR EMERITUS Eddy Karnieli


Abstract

Diabetes Mellitus has two main phenotypes, type 1 (T1D) and type 2 (T2D), and 90% of cases are T2D. T2D is a heterogenic complex metabolic disease, resulting from a combination of genetic and environmental factors, obesity being a major one. T2D is characterized by defects in insulin action at the tissue level (insulin resistance) and defects in pancreatic insulin secretion (beta cell dysfunction) or loss of function of pancreatic insulin-secreting cells. One of the key factors in insulin action in adipose and skeletal muscle tissue is the glucose transporter type 4 (GLUT4), an insulin stimulated glucose transporter. Insulin resistance in the skeletal muscle is associated with impaired function and cellular content of GLUT4. GLUT4-overexpression in skeletal muscle tissue can improve glucose homeostasis. Therefore, we created an engineered muscle construct (EMC) comprised of GLUT4-overexpressing (OEG4) cells.

The ability of the engineered implants to reduce fasting glucose levels was tested in Diet-induced obesity mice (DIO). Decrease and stabilization of fasting basal glucose levels were apparent up to 4 months after implantation. DIO mice implanted with OEG4-EMCs also had less lipid accumulation in their liver and secreted less aspartate transaminase (AST), one of the liver biomarkers. Whole genome sequencing and proteome analysis of the retrieved constructs showed elevated expression of muscle myokines and proteins, that have a beneficial effect on whole-body metabolic state. 

Additionally, we validated the efficiency of OEG4-EMCs in insulin-resistant Rag1-/-/MKR mice. Following administration of high glucose load, mice showed a lower increase in plasma glucose levels. Upon administration of insulin mice implanted with OEG4-EMCs showed decrease in blood glucose values indicating insulin sensitivity. Furthermore, glucose levels returned to basal levels faster than the control groups.

Our data indicate OEG4-EMC implant is an efficient mode for restoring insulin sensitivity and improving glucose homeostasis in diabetic mice models. Such procedure is a potential novel modality for T2D therapy.