Preparation of Microspheres Encapsulating a Recombinant TIMP-1 Adenovirus and their Inhibition of Proliferation of Hepatocellular Carcinoma Cells

Objective: The study aim was to prepare poly-DL-lactide-poly (PELA) microspheres encapsulatingrecombinant tissue inhibitors of metalloproteinase-1 (TIMP-1) in an adenovirus to investigate its inhibition on theproliferation of hepatocellular carcinoma cells HepG2.
Methods: Microspheres were prepared by encapsulatingthe recombinant TIMP-1 adenovirus into biodegradable PELA. The particle size, viral load, encapsulationefficiency and in-vitro release were measured. Microspheres were used to infect HepG2 cells, then infectionefficiency was examined under a fluorescent microscope and ultrastructural changes assessed by TEM. Expressionof TIMP-1 mRNA in HepG2 cells was examined by semi-quantitative RT-PCR and proliferation by MTT andcell growth curve assays.
Results: We successfully prepared microspheres encapsulating recombinant TIMP-1adenovirus with a diameter of 1.965μm, an encapsulation efficiency of 60.0%, a viral load of 10.5×108/mg andapproximate 60% of virus release within 120 h, the total releasing time of which was longer than 240 h. Themicrospheres were confirmed to be non-toxic with blank microspheres. Infected HepG2 cells could stably maintainin-vitro expression of TIMP-1, with significantly effects on biological behaviour
Conclusion: PELA microspheresencapsulating a recombinant TIMP-1 adenovirus can markedly inhibit the proliferation of HepG2 cells, whichprovides an experimental basis for polymer/chemistry-based gene therapy of hepatocellular carcinomas.