Gene therapy for hemophilia

Biomaterials as carrier, barrier and reactor for cell-based regenerative medicine

Cell therapy has achieved tremendous success in regenerative medicine in the past several decades. However, challenges such as cell loss, death and immune-rejection after transplantation still persist. Biomaterials have been designed as carriers to deliver cells to desirable region for local tissue regeneration; as barriers to protect transplanted cells from host immune attack; or as reactors to stimulate host cell recruitment, homing and differentiation. With the assistance of biomaterials, improvement in treatment efficiency has been demonstrated in numerous animal models of degenerative diseases compared with routine free cell-based therapy. Emerging clinical applications of biomaterial assisted cell therapies further highlight their great promise in regenerative therapy and even cure for complex diseases, which have been failed to realize by conventional therapeutic approaches.

Bio-Encapsulation for the Immune-Protection of Therapeutic Cells

The design of new technologies for treatment of human disorders is a complex and difficult task. The aim of this article is to explore state of art discussion of various techniques and materials involve in cell encapsulations. Encapsulation of cells within semi-permeable polymer shells or beads is a potentially powerful tool, and has long been explored as a promising approach for the treatment of several human diseases such as lysosomal storage disease (LSD), neurological disorders, Parkinsons disease, dwarfism, hemophilia, cancer and diabetes using immune-isolation gene therapy.

Encapsulation of factor IX-engineered mesenchymal stem cells in fibrinogen-alginate microcapsules enhances their viability and transgene secretion

Cell microencapsulation holds significant promise as a strategy for cellular therapies; however, inadequate survival and functionality of the enclosed cells limit its application in hemophilia treatment. Here, we evaluated the use of alginate-based microcapsules to enhance the viability and transgene secretion of human cord blood–derived mesenchymal stem cells in three-dimensional cultures. Given the positive effects of extracellular matrix molecules on mesenchymal stem cell growth, we tested whether fibrinogen-supplemented alginate microcapsules can improve the efficiency of encapsulated factor IX–engineered mesenchymal stem cells as a treatment of hemophilia B. We found that fibrinogen-supplemented alginate microcapsules (a) significantly enhanced the viability and proliferation of factor IX–engineered mesenchymal stem cells and (b) increased factor IX secretion by mesenchymal stem cells compared to mesenchymal stem cells in nonsupplemented microcapsules. Moreover, we observed the osteogenic, but not chondrogenic or adipogenic, differentiation capability of factor IX–engineered cord blood mesenchymal stem cells and their efficient factor IX secretion while encapsulated in fibrinogen-supplemented alginate microcapsules. Thus, the use of engineered mesenchymal stem cells encapsulated in fibrinogen-modified microcapsules may have potential application in the treatment of hemophilia or other protein deficiency diseases.

Sustained and therapeutic levels of human factor IX in hemophilia B mice implanted with microcapsules: key role of encapsulated cells

BACKGROUND

A gene therapy delivery system based on microcapsules enclosing recombinant cells engineered to secrete a therapeutic protein was explored in this study. In order to prevent immune rejection of the delivered cells, they were enclosed in non-antigenic biocompatible alginate microcapsules prior to being implanted intraperitoneally into mice. We have shown that encapsulated C2C12 myoblasts can temporarily deliver therapeutic levels of factor IX (FIX) in mice, but the C2C12 myoblasts elicited an immune response to FIX. In this study we report the use of mouse fetal G8 myoblasts secreting hFIX in hemophilia mice.

METHODS

Mouse G8 myoblasts were transduced with MFG-FIX vector. A pool of recombinant G8 myoblasts secreting approximately 1500 ng hFIX/10(6) cells/24 h in vitro were enclosed in biocompatible alginate microcapsules and implanted intraperitoneally into immunocompetent C57BL/6 and hemophilic mice.

RESULTS

Circulating levels of hFIX in treated mice reached approximately 400 ng/ml for at least 120 days (end of experiment). Interestingly, mice treated with encapsulated G8 myoblasts did not develop anti-hFIX antibodies. Activated partial thromboplastin time (APTT) of plasmas obtained from treated hemophilic mice was reduced from 107 to 82 sec on day 60 post-treatment, and whole blood clotting time (WBCT) was also corrected from 7-9 min before treatment to 3-5 min following microcapsule implantation. Further, mice were protected against bleeding following major trauma. Thus, the FIX delivery in vivo was biologically active.

CONCLUSIONS

Our findings suggest that the type of cells encapsulated play a key role in the generation of immune responses against the transgene. Further, a judicious selection of encapsulated cells is critical for achieving sustained gene expression. Our findings support the feasibility of encapsulated G8 myoblasts as a gene therapy approach for hemophilia B.

Rheumatological management of patients with hemophilia. Part 1: joint manifestations

The advent of factor VIII and IX replacement therapy has radically changed the physiognomy of hemophilia. In patients with no inhibitors, early replacement therapy shortens the immobilization and decreases the structural and functional alterations related to recurrent hemarthrosis. Routine prophylactic replacement therapy before or after the first episode of hemarthrosis is still rarely used in France. Recurrent hemarthrosis in the same joint can cause synovitis and chronic arthropathy. Injection synovectomy is now the preferred treatment, as opposed to secondary prophylactic replacement therapy and to arthroscopic or open synovectomy. The palliative treatment of chronic arthropathy is difficult and rests on analgesics and rehabilitation therapy, with orthotic devices and/or surgery where appropriate. The treatment of hemophilia is far more difficult in patients with inhibitors and, consequently, considerable hope is being placed in gene therapy, whose first results are encouraging.

Use of blood outgrowth endothelial cells for gene therapy for hemophilia A

A culture of human blood outgrowth endothelial cells (BOECs) was established from a sample of peripheral blood and was transfected using a nonviral plasmid carrying complementary DNA for modified human coagulation factor VIII (B domain deleted and replaced with green fluorescence protein). BOECs were then chemically selected, expanded, cryopreserved, and re-expanded in culture. Stably transfected BOECs were administered intravenously daily for 3 days to NOD/SCID mice at 4 cell dose levels (from 5 x 10(4) to 40 x 10(4) cells per injection). In 156 days of observation, mice showed levels of human FVIII that increased with cell dose and time. Mice in all cell dose groups achieved therapeutic levels (more than 10 ng/mL) of human FVIII, and mice in the 3 highest dose groups acquired levels that were normal (100-200 ng/mL) or even above the normal range (highest observed value, 1174 ng/mL). These levels indicate that the BOECs expanded in vivo after administration. When the mice were killed, it was found that BOEC accumulated only in bone marrow and spleen and that these cells retained endothelial phenotype and transgene expression. Cell doses used here would make scale-up to humans feasible. Thus, the use of engineered autologous BOECs, which here resulted in sustained and therapeutic levels of FVIII, may comprise an effective therapeutic strategy for use in gene therapy for hemophilia A.