Transduction of human recombinant proteins into mitochondria as a protein therapeutic approach for mitochondrial disorders

Protein Transduction Domain-Mediated Delivery of Recombinant Proteins and In Vitro Transcribed mRNAs for Protein Replacement Therapy of Human Severe Genetic Mitochondrial Disorders: The Case of Sco2 Deficiency

Mitochondrial disorders represent a heterogeneous group of genetic disorders with variations in severity and clinical outcomes, mostly characterized by respiratory chain dysfunction and abnormal mitochondrial function. More specifically, mutations in the human SCO2 gene, encoding the mitochondrial inner membrane Sco2 cytochrome c oxidase (COX) assembly protein, have been implicated in the mitochondrial disorder fatal infantile cardioencephalomyopathy with COX deficiency. Since an effective treatment is still missing, a protein replacement therapy (PRT) was explored using protein transduction domain (PTD) technology. Therefore, the human recombinant full-length mitochondrial protein Sco2, fused to TAT peptide (a common PTD), was produced (fusion Sco2 protein) and successfully transduced into fibroblasts derived from a SCO2/COX-deficient patient. This PRT contributed to effective COX assembly and partial recovery of COX activity. In mice, radiolabeled fusion Sco2 protein was biodistributed in the peripheral tissues of mice and successfully delivered into their mitochondria. Complementary to that, an mRNA-based therapeutic approach has been more recently considered as an innovative treatment option. In particular, a patented, novel PTD-mediated IVT-mRNA delivery platform was developed and applied in recent research efforts. PTD-IVT-mRNA of full-length SCO2 was successfully transduced into the fibroblasts derived from a SCO2/COX-deficient patient, translated in host ribosomes into a nascent chain of human Sco2, imported into mitochondria, and processed to the mature protein. Consequently, the recovery of reduced COX activity was achieved, thus suggesting the potential of this mRNA-based technology for clinical translation as a PRT for metabolic/genetic disorders. In this review, such research efforts will be comprehensibly presented and discussed to elaborate their potential in clinical application and therapeutic usefulness.

Serum Neuroglobin as a Potential Prognostic Biomarker for Cognitive Impairment After Intracerebral Hemorrhage

Objective

Stroke is closely related to dementia, but there are few prospective studies on cognitive decline after stroke in patients with cerebral hemorrhage. Neuroglobin is an oxygen-binding protein mainly expressed in brain neurons. The aim of our current study was to determine whether neuroglobin could serve as a biomarker for cognitive prognosis in patients with intracerebral hemorrhage (ICH).

Methods

Three hundred and sixteen patients with ICH were consecutively enrolled in a prospective study. Baseline data such as age and gender of ICH patients on admission were recorded. Serum neuroglobin concentrations were determined by enzyme-linked immunosorbent assay (ELISA). All ICH patients 3 months after onset were divided into post-stroke cognitive impairment group (PSCI) and non-PSCI group according to MoCA assessment results.

Results

The PSCI and Non-PSCI groups had serum neuroglobin concentrations of (4.7 ± 0.9) and (7.5 ± 1.1) ng/ml, respectively, with a statistically significant difference between the two groups (p < 0.05). Age, gender, LDL, FBG, SBP, DBP, NHISS, and Hematoma volume were found to be adversely connected with MoCA (p < 0.05), while education, HDL, and serum neuroglobin were found to be positively correlated with MoCA (p < 0.05). After controlling for baseline data, regression analysis revealed that serum neuroglobin was remained an efficient biomarker for predicting cognitive performance in individuals with ICH (p < 0.05). The diagnostic accuracy of blood neuroglobin concentration for PSCI in ICH patients was 72.6%, the sensitivity was 67.4%, and the specificity was 75.5%, according to receiver operating characteristic (ROC) curve analysis.

Conclusions

Serum neuroglobin may serve as a potential biomarker to predict cognitive decline after ICH.

Development of a novel PTD-mediated IVT-mRNA delivery platform for potential protein replacement therapy of metabolic/genetic disorders

The potential clinical applications of the powerful in vitro-transcribed (IVT)-mRNAs, to restore defective protein functions, strongly depend on their successful intracellular delivery and transient translation through the development of safe and efficient delivery platforms. In this study, an innovative (international patent-pending) methodology was developed, combining the IVT-mRNAs with the protein transduction domain (PTD) technology, as an efficient delivery platform. Based on the PTD technology, which enables the intracellular delivery of various cargoes intracellularly, successful conjugation of a PTD to the IVT-mRNAs was achieved and evaluated by band-shift assay and NMR spectroscopy. In addition, the PTD-IVT-mRNAs were applied and evaluated in two protein-disease models, including the mitochondrial disorder fatal infantile cardioencephalomyopathy and cytochrome c oxidase (COX) deficiency (attributed to SCO2 gene mutations) and β-thalassemia. The PTD-IVT-mRNA of SCO2 was successfully transduced and translated to the corresponding Sco2 protein inside the primary fibroblasts of a SCO2/COX-deficient patient, whereas the PTD-IVT-mRNA of β-globin was transduced and translated in bone marrow cells, derived from three β-thalassemic patients. The transducibility and the structural stability of the PDT-IVT-mRNAs, in both cases, were confirmed at the RNA and protein levels. We propose that our novel delivery platform could be clinically applicable as a protein therapy for metabolic/genetic disorders.

PTD-mediated delivery of α-globin chain into Κ-562 erythroleukemia cells and α-thalassemic (HBH) patients' RBCs ex vivo in the frame of Protein Replacement Therapy

Background

α-Thalassemia, a congenital hemoglobinopathy, is characterized by deficiency and/or reduced levels of α-globin chains in serious forms of α-thalassemia (HbH disease/Hb Bart’s). This research work deals with a Protein Replacement Therapy approach in order to manage α-thalassemia manifestations, caused by the excess of β-globin chain into HbH RBCs. The main goal was to produce the recombinant human α-globin chain in fusion with TAT, a Protein Transduction Domain, to ex vivo deliver it into HbH patients RBCs, to replace the endogenous missing α-globin chain.

Results

Cloning of the α-globin coding sequence, fused to the nucleotide sequence of TAT peptide was conducted and the human recombinant fusion proteins, 10xHis-Xa_SITE-α-globin-HA and 10xHis-Xa_SITE-TAT-α-globin-HA were produced. The ability of human recombinant 10xHis-Xa_SITE-α-globin-HA to interact in vitro with the previously produced 10xHis-Xa_SITE-TAT-β-globin-HA and form α-/β-globin heterodimers, was assessed and confirmed by size exclusion chromatography. The recombinant 10xHis-Xa_SITE-TAT-α-globin-HA was successfully delivered into human proerythroid K-562 cells, during the preliminary transduction evaluation experiments. Finally, the recombinant, TAT-fused α-globin was successfully transduced into RBCs, derived from HbH patients and reduced the formation of HbH-Inclusion Bodies, known to contain harmful β₄-globin chain tetramers.

Conclusions

Our data confirm the successful ex vivo transduction of recombinant α-globin chains in HbH RBCs to replace the missing a-globin chain and reduce the HbH-inclusion bodies, seen in α-thalassemias. These findings broaden the possibility of applying a Protein Replacement Therapy approach to module sever forms of α-thalassemia, using recombinant α-globin chains, through PTD technology.

Supplementary Information

The online version contains supplementary material available at 10.1186/s40709-021-00148-3.

In vivo biodistribution study of TAT-L-Sco2 fusion protein, developed as protein therapeutic for mitochondrial disorders attributed to SCO2 mutations

The rapid progress achieved in the development of many biopharmaceuticals had a tremendous impact on the therapy of many metabolic/genetic disorders. This type of fruitful approach, called protein replacement therapy (PRT), aimed to either replace the deficient or malfunctional protein in human tissues that act either in plasma membrane or via a specific cell surface receptor. However, there are also many metabolic/genetic disorders attributed to either deficient or malfunctional proteins acting intracellularly. The recent developments of Protein Transduction Domain (PTD) technology offer new opportunities by allowing the intracellular delivery of recombinant proteins of a given therapeutic interest into different subcellular sites and organelles, such as mitochondria and other entities. Towards this pathway, we applied successfully PTD Technology as a protein therapeutic approach, in vitro, in SCO2 deficient primary fibroblasts, derived from patient with mutations in human SCO2 gene, responsible for fatal, infantile cardioencephalomyopathy and cytochrome c oxidase deficiency.

In this work, we radiolabeled the recombinant TAT-L-Sco2 fusion protein with technetium-99 m to assess its in vivo biodistribution and fate, by increasing the sensitivity of detection of even low levels of the transduced recombinant protein. The biodistribution pattern of [^99mTc]Tc-TAT-L-Sco2 in mice demonstrated fast blood clearance, significant hepatobiliary and renal clearance. In addition, western blot analysis detected the recombinant TAT-L-Sco2 protein in the isolated mitochondria of several mouse tissues, including heart, muscle and brain. These results pave the way to further consider this PTD-mediated Protein Therapy Approach as a potentially alternative treatment of genetic/metabolic disorders.

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Radiolabeling of human recombinant mitochondrial TAT-L-Sco2 fusion protein with ^99mTc for the first time.

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[^99mTc]Tc-TAT-L-Sco2 can be successfully transduced into the mitochondria of peripheral tissues upon injection into animals.

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Protein Replacement Therapy, through PTD technology, can be a potential therapeutic approach for mitochondrial disorders.

Production and Transduction of a Human Recombinant β-Globin Chain into Proerythroid K-562 Cells To Replace Missing Endogenous β-Globin

Protein replacement therapy (PRT) has been applied to treat severe monogenetic/metabolic disorders characterized by a protein deficiency. In disorders where an intracellular protein is missing, PRT is not easily feasible due to the inability of proteins to cross the cell membrane. Instead, gene therapy has been applied, although still with limited success. β-Thalassemias are severe congenital hemoglobinopathies, characterized by deficiency or reduced production of the adult β-globin chain. The resulting imbalance of α-/β-globin chains of adult hemoglobin (α₂β₂) leads to precipitation of unpaired α-globin chains and, eventually, to defective erythropoiesis. Since protein transduction domain (PTD) technology has emerged as a promising therapeutic approach, we produced a human recombinant β-globin chain in fusion with the TAT peptide and successfully transduced it into human proerythroid K-562 cells, deficient in mature β-globin chain. Notably, the produced human recombinant β-globin chain without the TAT peptide, used as internal negative control, failed to be transduced into K-562 cells under similar conditions. In silico studies complemented by SDS-PAGE, Western blotting, co-immunoprecipitation and LC-MS/MS analysis indicated that the transduced recombinant fusion TAT-β-globin protein interacts with the endogenous native α-like globins to form hemoglobin α₂β₂-like tetramers to a limited extent. Our findings provide evidence that recombinant TAT-β-globin is transmissible into proerythroid K-562 cells and can be potentially considered as an alternative protein therapeutic approach for β-thalassemias.

Anesthetic Management in Mitochondrial Encephalomyopathy: A Case Report

We report on a morbidly obese 16-year-old boy (weight, 116 kg; height, 176 cm; body mass index, 35.5 kg/m²) with mitochondrial encephalomyopathy and a history of cerebral infarction, epilepsy, and severe mental retardation. The patient was scheduled for elective surgery under general anesthesia for multiple dental caries and entropion of the left eye. Preoperative examination results, including an electrocardiogram, were normal. No obvious cardiac function abnormalities were observed on echocardiography. Midazolam (10 mg) was administered orally as premedication 30 minutes before transfer to the operating room; however, the patient was uncooperative, and his body movements were difficult to control upon entering the operating room. This complicated our attempts to establish a peripheral intravenous line and necessitated volatile inhalational induction, followed by maintenance using total intravenous anesthesia. General anesthesia was used to minimize metabolic system stress. We did not use an infusion solution containing sodium lactate. The operation and subsequent clinical course until discharge were uneventful. Because aerobic metabolism is already compromised in patients with mitochondrial encephalomyopathy, anesthetic management should be designed to avoid placing additional stress on the metabolic system.

The potential role of cell penetrating peptides in the intracellular delivery of proteins for therapy of erythroid related disorders

The erythroid related disorders (ERDs) represent a large group of hematological diseases, which in most cases are attributed either to the deficiency or malfunction of biosynthetic enzymes or oxygen transport proteins. Current treatments for these disorders include histo-compatible erythrocyte transfusions or allogeneic hematopoietic stem cell (HSC) transplantation. Gene therapy delivered via suitable viral vectors or genetically modified HSCs have been under way. Protein Transduction Domain (PTD) technology has allowed the production and intracellular delivery of recombinant therapeutic proteins, bearing Cell Penetrating Peptides (CPPs), into a variety of mammalian cells. Remarkable progress in the field of protein transduction leads to the development of novel protein therapeutics (CPP-mediated PTs) for the treatment of monogenetic and/or metabolic disorders. The “concept” developed in this paper is the intracellular protein delivery made possible via the PTD technology as a novel therapeutic intervention for treatment of ERDs. This can be achieved via four stages including: (i) the production of genetically engineered human CPP-mediated PT of interest, since the corresponding native protein either is missing or is mutated in the erythroid progenitor cell (ErPCs) or mature erythrocytes of patients; (ii) isolation of target cells from the peripheral blood of the selected patients; (iii) ex vivo transduction of cells with the CPP-mediated PT of interest; and (iv) re-administration of the successfully transduced cells back into the same patients.

Guidelines for genetic study of aniridia

INTRODUCTION

Aniridia is a panocular disorder which occurs in 1/50,000 to 1/100,000 live births and can appear either in isolated form or in the context of a syndrome. Isolated aniridia is inherited as an autosomal dominant condition and is caused by mutations of the PAX6 gene. A variety of techniques and methodologies within molecular genetics and cytogenetics are used to study these mutations.

OBJECTIVE

To identify the different aspects of this disease and to provide a guide for proper genetic diagnosis leading to improved clinical management of the disease.

DEVELOPMENT

Aniridia is an autosomal dominant disease that primarily affects the iris, though it can impact most of the ocular structures. The disease is mainly caused by mutations in the PAX6 gene located on chromosome 11p13 which encodes a transcription factor that is involved in the development of the eye. Genetic analysis of aniridia is complex and requires the use of both molecular genetics and cytogenetics techniques. These procedures are indicated in all cases of aniridia. It is important bear certain clinical and technical aspects in mind prior to starting analysis or providing genetic counseling for patients and their families.

CONCLUSIONS

The use of molecular genetic techniques in the genetic diagnosis of aniridia enables patients and their families to receive better clinical management.

Protein transduction domain-hA20 fusion protein protects endothelial cells against high glucose-induced injury

We constructed a plasmid containing a protein transduction domain (PTD) and a human A20 (hA20) gene fragment; the fusion protein was obtained by highly expressing this plasmid in the yeast Pichia pastoris GS115. The plasmid was obtained by adding 9xArg and EcoRІ recognition sites to the end of the primer, and 6xHis-Tag and NotІ recognition sites to its end. After sequencing, the hA20 gene fragment was inserted into plasmid pPIC9k to construct expression vector pPIC9k-PTD-hA20; then, we transfected GS115 with the vector and induced PTD-hA20 protein expression. We purified protein from the yeast fermentation supernatant using a nickel column. Human umbilical vein endothelial cells (HUVECs) were cultured in high glucose medium (30 mM glucose) and in high glucose medium containing different concentrations of protein. Apoptosis of HUVECs was assayed by TUNEL 72 h later. The biological activity tests indicated that the fusion protein not only passed through the cell membrane freely, but also inhibited apoptosis of HUVECs induced by high glucose levels. We conclude that the fusion protein PTD-hA20 has potential for clinical use.