Correction of anemia in uremic rats by intramuscular injection of lentivirus carrying an erythropoietin gene

A lentiviral gene therapy strategy for the in vitro production of feline erythropoietin

Nonregenerative anemia due to chronic renal failure is a common problem in domestic cats. Unfortunately, administration of recombinant human erythropoietin often only improves anemia temporarily due to antibody development. In this in vitro study, feline erythropoietin cDNA was cloned from feline renal tissue and utilized in the construction of a replication-defective lentiviral vector. The native recombinant feline erythropoietin (rfEPO) sequence was confirmed by sequencing. Upon viral vector infection of human 293H cells, Crandall Renal Feline Kidney cell line and primary feline peripheral blood mononuclear cells, bioactive rfEPO protein was produced. The presence of cellular rfEPO cDNA was confirmed by standard PCR, production of abundant rfEPO mRNA was confirmed by real-time PCR, and secretion of rfEPO protein was demonstrated by Western blot analyses, while rfEPO protein bioactivity was confirmed via an MTT proliferation bioassay. This in vitro study demonstrates the feasibility of a replication-defective lentiviral vector delivery system for the in vitro production of biologically active feline erythropoietin. Anemic cats with chronic renal failure represent a potential in vivo application of a lentiviral gene therapy system.

Enhancer of polycomb1 lessens neointima formation by potentiation of myocardin-induced smooth muscle differentiation

OBJECTIVE

Previously, we reported that enhancer of polycomb1 (Epc1) induces skeletal muscle differentiation through the serum response factor (SRF). Considering that SRF plays a critical role in vascular smooth muscle cell (VSMC) differentiation, we expected that Epc1 also works in VSMCs. Here we examined the effect of Epc1 on neointima formation after arterial balloon injury and the underlying mechanism.

METHODS

Epc1 expression was examined in carotid artery injury or VSMC models. Interaction with myocardin (Myocd), a master regulator of smooth muscle differentiation, was examined by immunoprecipitation or promoter analysis with smooth muscle (SM) 22α promoter. Finally, we investigated whether local delivery of Epc1 regulated neointimal formation after injury.

RESULTS

Epc1 expression was down-regulated during proliferation induced by platelet-derived growth factor BB, whereas it was upregulated during differentiation in VSMCs. Forced expression of Epc1 induced VSMC differentiation. Epc1 physically interacted with Myocd to synergistically activate SM22α promoter activity. Transient transfection of Epc1 enhanced the physical interaction between Myocd and SRF, whereas that interaction was reduced when A10 cells were treated with siRNA for Epc1. Local delivery of Epc1 significantly reduced neointima formation induced by balloon injury.

CONCLUSIONS

Our results indicate that Epc1 induces VSMC differentiation by interacting with Myocd to induce SRF-dependent smooth muscle genes. We propose that Epc1 acts as a novel negative regulator of neointima formation after carotid injury.

Emerging technologies in the delivery of erythropoietin for therapeutics

Deciphering the function of proteins and their roles in signaling pathways is one of the main goals of biomedical research, especially from the perspective of uncovering pathways that may ultimately be exploited for therapeutic benefit. Over the last half century, a greatly expanded understanding of the biology of the glycoprotein hormone erythropoietin (Epo) has emerged from regulator of the circulating erythrocyte mass to a widely used therapeutic agent. Originally viewed as the renal hormone responsible for erythropoiesis, recent in vivo studies in animal models and clinical trials demonstrate that many other tissues locally produce Epo independent of its effects on red blood cell mass. Thus, not only its hematopoietic activity but also the recently discovered nonerythropoietic actions in addition to new drug delivery systems are being thoroughly investigated in order to fulfill the specific Epo release requirements for each therapeutic approach. The present review focuses on updating the information previously provided by similar reviews and recent experimental approaches are presented to describe the advances in Epo drug delivery achieved in the last few years and future perspectives.

Epo delivery by genetically engineered C2C12 myoblasts immobilized in microcapsules

ver the last half century, the use of erythropoietin (Epo) in the management of malignancies has been extensively studied. Originally viewed as the renal hormone responsible for red blood cell production, many recent in vivo and clinical approaches demonstrate that various tissues locally produce Epo in response to physical or metabolic stress. Thus, not only its circulating erythrocyte mass regulator activity but also the recently discovered nonhematological actions are being thoroughly investigated in order to fulfill the specific Epo delivery requirements for each therapeutic approach.

Delivery of factor VIII gene into skeletal muscle cells using lentiviral vector

PURPOSE

This study was designed to investigate whether transduction of lentiviral vectors (LV) carrying human coagulation factor VIII (hFVIII) cDNA into skeletal muscle could increase circulating hFVIII concentrations.

MATERIALS AND METHODS

A LV containing bacterial LacZ gene as a control or human FVIII gene was intramuscularly administered into the thigh muscle of 5 weeks old Sparague-Dawley rats. The plasma human FVIII concentration and neutralizing anti-FVIII antibodies were measured for up to 12 weeks in these experimental animals.

RESULTS

The plasma human FVIII levels in the rats injected with LV carrying FVIII cDNA peaked at post-injection 1st week (5.19 +/- 0.14 ng/mL vs. 0.21 +/- 0.05 ng/mL in control rats , p < 0.05). Elevated hFVIII concentrations were maintained for 4 weeks (2.52 +/- 0.83 ng/mL vs. 0.17 +/- 0.08 ng/mL in control rats, p < 0.05) after a single intramuscular injection. In the Bethesda assay, neutralizing antibodies for FVIII protein were detected only in FVIII-LV injected rats by the 10th week, but not in control rats.

CONCLUSION

This study suggested that a single administration of an advanced generation LV carrying the human FVIII cDNA resulted in elevation of FVIII level in immune competent rats, and that this gene transfer approach to the skeletal muscle could be an effective tool in treatment of hemophilia A.

Optimizing the management of renal anemia: challenges and new opportunities

Erythropoiesis stimulating agents (ESAs) are the main tool to achieve anemia correction in CKD patients. At present six different ESAs are available: epoetin alpha, epoetin beta, epoetin omega, epoetin delta, darbepoetin alpha, and very recently CERA. From one side the patent of older ESAs have expired, and biosimilars (for the moment only of epoetin alpha) have been approved for use in Europe by the European Medicines Agency. However, a number of issues about bioequivalence and how to test it are still to be solved completely. In the mean time pharmaceutical research has kept on working, developing new ESAs and alternative strategies for stimulating erythropoiesis. In this review we present and discuss these points.

Potential Use of Gene Transfer in Athletic Performance Enhancement

After only a short history of three decades from concept to practice, gene therapy has recently been shown to have potential to treat serious human diseases. Despite this success, gene therapy remains in the realm of experimental medicine, and much additional preclinical and clinical study will be necessary for proving the efficacy and safety of this approach in the treatment of diseases in humans. However, a potential complicating factor is that advances in gene transfer technology could be misused to enhance athletic performance in sports, in a practice termed "gene doping". Moreover, gene doping could be a precursor to a broader controversial agenda of human "genetic enhancement" with the potential for a significant long-term impact on society. This review addresses the possible ways in which knowledge and experience gained in gene therapy in animals and humans may be abused for enhancing sporting prowess. We provide an overview of recent progress in gene therapy, with potential application to gene doping and with the major focus on candidate performance-enhancement genes. We also discuss the current status of preclinical studies and of clinical trials that use these genes for therapeutic purposes. Current knowledge about the association between the natural "genetic make-up" of humans and their physical characteristics and performance potential is also presented. We address issues associated with the safety of gene transfer technologies in humans, especially when used outside a strictly controlled clinical setting, and the obstacles to translating gene transfer strategies from animal studies to humans. We also address the need for development and implementation of measures to prevent abuse of gene transfer technologies, and to pursue research on strategies for its detection in order to discourage this malpractice among athletes.

Control of erythropoietin gene expression and its use in medicine

Erythropoietin (EPO) gene expression is under the control of inhibitory (GATA-2, NF-kappaB) and stimulatory (hypoxia-inducible transcription factor [HIF]-2, hepatocyte nuclear factor [HNF]-4alpha [alpha]) transcription factors. EPO deficiency is the main cause of the anemia in chronic kidney disease (CKD) and a contributing factor in the anemias of inflammation and cancer. Small, orally active compounds capable of stimulating endogenous EPO production are in preclinical or clinical trials for treatment of anemia. These agents include stabilizers of the HIFs that bind to the EPO enhancer and GATA inhibitors which prevent GATA from suppressing the EPO promoter. While HIF stabilizing drugs may prove useful as inexpensive second-line choices, at present, their side effects--particularly tumorigenicity--preclude their use as first-choice therapy. As an alternative, EPO gene therapy has been explored in animal studies and in trials on CKD patients. Here, a major problem is immunogenicity of ex vivo transfected implanted cells and of the recombinant protein produced after ex vivo or in vivo EPO complementary DNA (cDNA) transfer. Recombinant human EPO (rhEPO) engineered in Chinese hamster ovary (CHO) cell cultures (epoetin alpha and epoetin beta [beta]) and its hyperglycosylated analogue darbepoetin alpha are established and safe drugs to avoid allogeneic red blood cell transfusion. Gene-activated EPO (epoetin delta [delta]) from human fibrosarcoma cells (HT-1080) has recently been launched for use in CKD. It is important to know the basics of the technologies, production processes, and structural properties of the novel anti-anemic strategies and drugs.