Recombinant human factor IX produced from transgenic porcine milk

Characterization of Enlarged Tongues in Cloned Piglets

Although the efficiency of cloning remains very low, this technique has become the most reliable way to produce transgenic pigs. However, the high rate of abnormal offspring such as an enlarged tongue lowers the cloning efficiency by reducing the early survivability of piglets. Thus, the present study was conducted to identify the characteristics of the enlarged tongue from cloned piglets by histologic and transcriptomic analysis. As a result, it was observed that the tissues from enlarged tongues (n = 3) showed isolated and broken muscle bundles with wide spaces while the tissues from normal tongues (n = 3) showed the tight connection of muscle bundles without space by histological analysis. Additionally, transmission electron microscopy results also showed the formation of isolated and broken muscle bundles in enlarged tongues. The transcriptome analysis showed a total of 197 upregulated and 139 downregulated genes with more than 2-fold changes in enlarged tongues. Moreover, there was clear evidence for the difference between groups in the muscle system process with high relation in the biological process by gene ontology analysis. The analysis of the Kyoto Encyclopedia of Gene and Genomes pathway of differentially expressed genes indicated that the pentose phosphate pathway, glycolysis/gluconeogenesis, and glucagon signaling pathway were also involved. Conclusively, our results could suggest that the abnormal glycolytic regulation may result in the formation of an enlarged tongue. These findings might have the potential to understand the underlying mechanisms, abnormal development, and disease diagnosis in cloned pigs.

Purification of Modified Therapeutic Proteins Available on the Market: An Analysis of Chromatography-Based Strategies

Proteins, which have inherent biorecognition properties, have long been used as therapeutic agents for the treatment of a wide variety of clinical indications. Protein modification through covalent attachment to different moieties improves the therapeutic's pharmacokinetic properties, affinity, stability, confers protection against proteolytic degradation, and increases circulation half-life. Nowadays, several modified therapeutic proteins, including PEGylated, Fc-fused, lipidated, albumin-fused, and glycosylated proteins have obtained regulatory approval for commercialization. During its manufacturing, the purification steps of the therapeutic agent are decisive to ensure the quality, effectiveness, potency, and safety of the final product. Due to the robustness, selectivity, and high resolution of chromatographic methods, these are recognized as the gold standard in the downstream processing of therapeutic proteins. Moreover, depending on the modification strategy, the protein will suffer different physicochemical changes, which must be considered to define a purification approach. This review aims to deeply analyze the purification methods employed for modified therapeutic proteins that are currently available on the market, to understand why the selected strategies were successful. Emphasis is placed on chromatographic methods since they govern the purification processes within the pharmaceutical industry. Furthermore, to discuss how the modification type strongly influences the purification strategy, the purification processes of three different modified versions of coagulation factor IX are contrasted.

Structural and functional characterization of recombinant human growth hormone isolated from transgenic pig milk

This study aimed to establish and reproduce transgenic pigs expressing human growth hormone (hGH) in their milk. We also aimed to purify hGH from the milk, to characterize the purified protein, and to assess the potential of our model for mass production of therapeutic proteins using transgenic techniques. Using ~15.5 L transgenic pig milk, we obtained proteins with ≥ 99% purity after three pre-treatments and five column chromatography steps. To confirm the biosimilarity of our milk-derived purified recombinant hGH (CGH942) with commercially available somatropin (Genotropin), we performed spectroscopy, structural, and biological analyses. We observed no difference between the purified protein and Genotropin samples. Furthermore, rat models were used to assess growth promotion potential. Our results indicate that CGH942 promotes growth, by increasing bone development and body weight. Toxicity assessments revealed no abnormal findings after 4 weeks of continuous administration and 2 weeks of recovery. The no-observed-adverse-effect level for both males and females was determined to be 0.6 mg/kg/day. Thus, no toxicological differences were observed between commercially available somatropin and CGH942 obtained from transgenic pig milk. In conclusion, we describe a transgenic technique using pigs, providing a new platform to produce human therapeutic proteins.

Application of Genetically Engineered Pigs in Biomedical Research

Progress in genetic engineering over the past few decades has made it possible to develop methods that have led to the production of transgenic animals. The development of transgenesis has created new directions in research and possibilities for its practical application. Generating transgenic animal species is not only aimed towards accelerating traditional breeding programs and improving animal health and the quality of animal products for consumption but can also be used in biomedicine. Animal studies are conducted to develop models used in gene function and regulation research and the genetic determinants of certain human diseases. Another direction of research, described in this review, focuses on the use of transgenic animals as a source of high-quality biopharmaceuticals, such as recombinant proteins. The further aspect discussed is the use of genetically modified animals as a source of cells, tissues, and organs for transplantation into human recipients, i.e., xenotransplantation. Numerous studies have shown that the pig (Sus scrofa domestica) is the most suitable species both as a research model for human diseases and as an optimal organ donor for xenotransplantation. Short pregnancy, short generation interval, and high litter size make the production of transgenic pigs less time-consuming in comparison with other livestock species This review describes genetically modified pigs used for biomedical research and the future challenges and perspectives for the use of the swine animal models.

Production of biologically active human factor IX-Fc fusion protein in the milk of transgenic mice

OBJECTIVE

To investigate the feasibility of producing human IgG1 Fc fragment fused factor IX (FIX-Fc) in the milk of transgenic animals, for an alternative possible solution to the unmet need of FIX-Fc products for hemophilia B treatment.

RESULTS

Six founder lines of transgenic mice harboring FIX-Fc cassette designed to be expressed specifically in the mammary gland were generated. FIX-Fc protein was secreted into the milk of transgenic mice with preserved biological activity (with the highest value of 6.2 IU/mL), similar to that of the non-fused FIX transgenic milk. RT-PCR and immunofluorescence analysis confirmed that FIX-Fc was specifically expressed in the mammary gland. The blood FIX clotting activities were unchanged, and no apparent health defects were observed in the transgenic mice. Moreover, the stability of FIX protein in milk was increased by the Fc fusion.

CONCLUSIONS

It is feasible to produce biologically functional FIX-Fc in the mammary gland of transgenic mice. Our preliminary results provide a foundation for the potential scale-up production of FIX-Fc in the milk of dairy animals.

A galactopoiesis accordant yield of functional recombinant human factor IX from homozygous transgenic pigs requires a large amount of vitamin K supplementation

Transgenic pigs failed to accord milk yield curve to lactate rhFIX-a vitamin K (VK) dependent protein even fed with VK enriched to 8 times higher than nutritional requirement. A further higher VK supplementation may be required. Homozygous transgenic sows (n = 4, 200 kg) at their 3rd nursing were divided into control and treatment groups and respectively received VK enriched and further menadione (soluble VK) supplemented diet (220 mg/kg VK enriched diet) for 33 days. At next lactation, control sows than received treatment and previous treated were fed on control diet. Results revealed that menadione treatment increased milk bioactivity of rhFIX from the 7th day of 73 to the 21st day of 153 IU/mL; it gradually decreased to 96 IU/mL on 35th day of lactation. Under control feeding, bioactivity remained relatively unchanged. However, milk rhFIX concentration and ratio of activated rhFIX responded little to the treatment. The menadione-induced bioactivity curve agrees with the known lactation pattern of sow means rhFIX secretion is still galactopoietic but requires high VK intake to show. The ineffectual VK spend on lactational carboxylation might be common in other mammary VK dependent expression system but can be effectively overcome by a high supplementation of menadione with a 5-folds improvement in quality.

Characterization of IXINITY® (Trenonacog Alfa), a Recombinant Factor IX with Primary Sequence Corresponding to the Threonine-148 Polymorph

The goal of these studies was to extensively characterize the first recombinant FIX therapeutic corresponding to the threonine-148 (Thr-148) polymorph, IXINITY (trenonacog alfa [coagulation factor IX (recombinant)]). Gel electrophoresis, circular dichroism, and gel filtration were used to determine purity and confirm structure. Chromatographic and mass spectrometry techniques were used to identify and quantify posttranslational modifications. Activity was assessed as the ability to activate factor X (FX) both with and without factor VIIIa (FVIIIa) and in a standard clotting assay. All results were consistent across multiple lots. Trenonacog alfa migrated as a single band on Coomassie-stained gels; activity assays were normal and showed <0.002 IU of activated factor IX (FIXa) per IU of FIX. The molecule has >97%  γ-carboxylation and underwent the appropriate structural change upon binding calcium ions. Trenonacog alfa was activated normally with factor XIa (FXIa); once activated it bound to FVIIIa and FXa. When activated to FIXa, it was inhibited efficiently by antithrombin. Glycosylation patterns were similar to plasma-derived FIX with sialic acid content consistent with the literature reports of good pharmacokinetic performance. These studies have shown that trenonacog alfa is a highly pure product with a primary sequence and posttranslational modifications consistent with the common Thr-148 polymorphism of plasma-derived FIX.

In vivo efficacy of human recombinant factor IX produced by the human hepatoma cell line HuH-7

INTRODUCTION

Post-translational modifications of the CHO-cell-derived-recombinant human factor IX (FIX) currently used for the treatment of hemophilia B (HB) are different from plasma derived FIX. Our previous studies described a rFIX (HIX) having better profile of post-translational modifications than rFIX produced by CHO cells. The aim of the study consisted to verify the improved post-translational modifications effect of HIX on in vivo recovery.

MATERIALS AND METHODS

HIX has been produced in a bioreactor and then purified from supernatants. In vitro activation and activity were evaluated measured by thrombin generation tests (TGT) and compared to commercial molecules, Benefix(®) , Mononine(®) . The three molecules were then administrated (i.v.) to FIX-knockout mice and two minutes after injection, blood samples were collected and subjected to human FIX-specific-ELISA and TGT.

RESULTS

The clotting function of HIX, activation courses of HIX by FXIa and FVIIa-TF complex appear normal as did activation of Benefix(®) , Mononine(®) and TG constants of each FIX were equivalent. After injection to HB mice, circulating HIX did not present any significant difference in term of antigen value with Benefix(®) . Intriguingly, TGT were clearly exhibiting a better velocity for HIX than Benefix(®) and Mononine(®) . These data suggested that HIX may improve in vivo coagulant efficacy in comparison with the two commercial FIX injected at the same dose.

CONCLUSION

The study shows that HuH-7-derived-rFIX has better in vivo haemostatic activity in hemophilia B mice compared to the reference rFIX molecule despite similar in vivo recovery rates, suggesting that HuH-7 cells could represent an effective cellular system for production of rFIX.