Expression of human factor IX by microencapsulated recombinant fibroblasts

Area of Science:

• Biotechnology
• Gene Therapy
• Cell Biology

Background:

• Hemophilia B is a genetic bleeding disorder caused by deficiency of clotting factor IX (FIX).
• Current treatments often involve regular infusions of plasma-derived or recombinant FIX.
• A cell-based delivery system could offer a more convenient and sustained therapeutic option.

Purpose of the Study:

• To engineer mouse fibroblast cell lines capable of secreting functional human FIX.
• To assess the feasibility of protecting these engineered cells within biocompatible microcapsules for implantation.
• To evaluate the viability, proliferation, and FIX secretion of encapsulated cells.

Main Methods:

• Mouse Ltk- fibroblast cells were transfected with human FIX cDNA.
• High-FIX-secreting clones were isolated and characterized.
• Cells were encapsulated in alginate-polylysine-alginate microcapsules.
• Secreted FIX biological activity, gamma-carboxylation, and immunoreactivity were analyzed.

Main Results:

• Engineered fibroblasts secreted biologically active human FIX, with appropriate gamma-carboxylation.
• Encapsulated cells maintained high viability (70-90%) and proliferated within microcapsules.
• Encapsulated cells continued to secrete FIX at rates comparable to unencapsulated cells.
• Recovered FIX from encapsulated cells showed identical biological activity and characteristics to that from unencapsulated cells.

Conclusions:

• Fibroblasts engineered to secrete recombinant human FIX can function effectively within alginate microcapsules.
• This microencapsulation approach supports cell survival, proliferation, and sustained secretion of active FIX.
• The study demonstrates the feasibility of using microencapsulated allogeneic cells for somatic gene therapy of hemophilia B.