These are exciting times in the scientific world. The public all over the world is fascinated by the spectacular advances in gene therapy, sequencing of the human genome, and stem cell research. These advances promise to prevent, correct or modulate genetic and acquired diseases, which use genes to produce therapeutic proteins or inhibit aberrant protein production.
The launching of the human proteome project has turned functional genomics and proteomics into powerful bullworks, which will give us an integrated scenario of turning nucleic acids into therapeutics. The development of effective nucleic acid therapeutics demands teamwork among scientists with expertise in molecular and cell biology, biochemistry, biophysics, polymer chemistry, colloid science, pharmaceutics, and medicine.
In the last decade, significant progress has been made in the use of nucleic acids, such as plasmid DNA, antisense oligonucleotides, siRNA, ribozymes, peptide nucleic acids (PNA) and aptamer nucleic acids for nucleic acid therapy.
Ongoing Research Projects in Mahato's Lab
Design and Synthesis of Novel Polymer and Lipid Carriers
We are working on the Site-specific Delivery of Oligonucleotides and siRNA to Hepatocytes or Hepatic Stellate Cells for treatment of hepatitis and liver fibrosis. We have recently shown that the conjugation of triplex forming oligonucleotides to mannose-6-phosphate-bovine serum albumin (M6P-BSA) can significantly enhance TFO delivery to hepatic stellate cells and this M6P-BSA-TFO has the potential to treat liver fibrosis by inhibiting collagen synthesis (Ye et al, Biochemistry. 2005, 44(11):4466-76 and Bioconjug Chem, 2006;17(3):823-30).
We have also shown that cholesterol conjugation can significantly increase the hepatic uptake of TFO upon systemic administration in liver fibrotic rats (Cheng et al., J Pharmacol Exp Ther. 2006; 317(2):797-805). We also determined the biodistribution and pharmacokinetic profiles of TFO after systemic administration in normal and fibrotic rats (Cheng et al, Mol Pharm. 2005, 2(3): 206-17). Currently, we are also working on site-specific delivery of TFO and chemically synthesized siRNA for treating hepatitis and liver fibrosis by bioconjugation with polymers and lipids with or without a targeting ligand.
We are developing several novel amphiphilic copolymers and lipopolymers for use as micellar delivery of small molecular weight hydrophobic anti-cancer drugs (Danquah et al ., Biomaterials. 2010 Mar;31(8):2358-70. and Li et al., Biomacromolecules. 2010 Oct 11;11(10):2610-20.
Design and Construction of Plasmid and Adenovirus-based Gene Expression Systems
Despite tremendous progress in islet isolation, culture, and preservation, the clinical use of human islet transplantation for treating type I diabetes is limited due to post-transplantation challenges to the islets such as the failure to revascularize and immune destruction of the islet graft (Narang and Mahato, Pharmacol Rev.2006;58(2):194-243).
We are working on genetic modification of human islets prior to transplantation to prevent beta-cell death. To provide synergistic effect, we are trying to deliver more than one therapeutic genes using plasmid and adenoviral vectors. We also work on cationic lipids and polymers for gene delivery. Based on our recent findings \ (Mahato et al, Mol Ther. 2003, 7(1):89-100; Narang et al, Pharm Res. 2004; 21(1):15-25 and 2006, Sep Issue; Cheng et al. Gene Ther. 2004;11(14):1105-16), we are currently working on construction and characterization of adenoviral vectors with different therapeutic genes for ex vivo infection into human and rat islets. In addition, we are also working on siRNA delivery to human and rat islets for silencing antiapoptotic genes for improving the outcome of islet transplantation.
Combination of Stem Cells and Gene Delivery for Improving Islet Transplantation
Human bone marrow-derived mesenchymal stem cells (hBMSCs) have the potential to improve the outcome of human islet transplantation by repairing damaged islets and modulating immune responses. Co-expression of human hepatocyte growth factor (hHGF) and interleukin-1 receptor antagonist (hIL-1Ra) promotes revascularization and inhibits apoptosis of islet cells. We will test the hypotheses that hBMSCs can retain immunosuppressive effect after co-transplantation with human islets, and co-expression of growth factor and antiapoptotic genes could further improve the outcome of islet transplantation. This will greatly decrease the number of islets required to achieve normoglycemia.
siRNA Delivery for Treatment of Hepatitis, Liver Fibrosis and Diabetes
We are working on site-specific delivery of siRNA for treating liver fibrosis and ex vivo therapy for treating type I diabetes. We are also working on the design/construction of plasmid and adenovirus-based shRNA for treating these diseases.
Liver Ischemia Reperfusion Injury and Liver Transplantation
Hedgehog (Hh) signaling is required for endodermal commitment and hepatogenesis, the possibility that it regulates liver injury after ischemia reperfusion (I/R) has not been considered. We determined the expression pattern of Hh signaling and its role in liver injury following I/R using Hh antagonist cyclopamine (CYA). We plan to further this approach by selectively targeting cyclopamine to the liver using Gal-PEG-HBCD.