Viral vectors for gene therapy: past, present and future

Safeguards for Using Viral Vector Systems in Human Gene Therapy: A Resource for Biosafety Professionals Mitigating Risks in Health Care Settings

Introduction

Health care workers who work daily with human body fluids and hazardous drugs are among those at the highest risk of occupational exposure to these agents. The Occupational Safety and Health Administration's (OSHA) Bloodborne Pathogens Standard (29 CFR 1910.1030) prescribes safeguards to protect workers against health hazards related to bloodborne pathogens. Similarly, the United States Pharmacopeia General Chapter 800 (USP <800>), a standard first published in February 2016 and implementation required by December 2019, addresses the occupational exposure risks of health care workers at organizations working with hazardous drugs. With emerging technologies in the field of gene therapy, these occupational exposure risks to health care workers now extend beyond those associated with bloodborne pathogens and hazardous drugs and now include recombinant DNA. The fifth edition of the Biosafety in Microbiological and Biomedical Laboratories (BMBL) and the National Institutes of Health Guidelines for Research Involving Recombinant or Synthetic Nucleic Acid Molecules (NIH Guidelines) mostly govern work with biohazardous agents and recombinant DNA in a laboratory research setting. When gene therapy products are utilized in a hospital environment, health care workers have very few resources to identify and reduce the risks associated with product use during and after the administration of treatments.

Methods

At the Abigail Wexner Research Institute at Nationwide Children's Hospital, a comprehensive gap analysis was executed between the research and health care environment to develop a program for risk mitigation. The BMBL, NIH Guidelines, World Health Organization Biosafety Manual, OSHA Bloodborne Pathogens Standard, and USP <800> were used to develop a framework for the gap analysis process.

Results

The standards and guidelines for working with viral vector systems in a research laboratory environment were adapted to develop a program that will mitigate the risks to health care workers involved in the preparation, transportation, and administration of gene therapies as well as subsequent patient care activities. The gap analysis identified significant differences in technical language used in daily operations, work environment, training and education, disinfection practices, and policy development between research and health care settings. These differences informed decisions and helped the organization develop a collaborative framework for risk mitigation when a gene therapy product enters the health care setting.

Discussion

With continuing advances in the field of gene therapy, the oversight structure needs to evolve for the health care setting. To deliver the best outcomes to the patients of these therapies, researchers, Institutional Biosafety Committees, and health care workers need to collaborate on training programs to safeguard the public trust in the use of this technology both in clinical trials and as FDA-approved therapeutics.

Viral Vector Systems for Gene Therapy: A Comprehensive Literature Review of Progress and Biosafety Challenges

INTRODUCTION

National Institutes of Health (NIH) defines gene therapy as an experimental technique that uses genes to treat or prevent disease. Although gene therapy is a promising treatment option for a number of diseases (including inherited disorders, some types of cancer, and certain viral infections), the technique remains risky and is still under study to make sure that it will be effective and safe.

METHODS

Applications of viral vectors and nonviral gene delivery systems have found an encouraging new beginning in gene therapy in recent years. Although several viral vectors and nonviral gene delivery systems have been developed in the past 3 decades, no one delivery system can be applied in gene therapy to all cell types in vitro and in vivo. Furthermore, the use of viral vector systems (both in vitro and in vivo) present unique occupational health and safety challenges. In this review article, we discuss the biosafety challenges and the current framework of risk assessment for working with the viral vector systems.

DISCUSSION

The recent advances in the field of gene therapy is exciting, but it is important for scientists, institutional biosafety committees, and biosafety officers to safeguard public trust in the use of this technology in clinical trials and make conscious efforts to engage the public through ongoing forums and discussions.

Nanoparticle Delivery Systems for DNA/RNA and their Potential Applications in Nanomedicine

The rapid development of nanotechnology has a great influence on the fields of biology, physiology, and medicine. Over recent years, nanoparticles have been widely presented as nanocarriers to help the delivery of gene, drugs, and other therapeutic agents with cellular targeting ability. Advances in the understanding of gene delivery and RNA interference (RNAi)-based therapy have brought increasing attention to understanding and tackling complex genetically related diseases, such as cancer, cardiovascular and pulmonary diseases, autoimmune diseases and infections. The combination of nanocarriers and DNA/RNA delivery may potentially improve their safety and therapeutic efficacy. However, there still exist many challenges before this approach can be practiced in the clinic. In this review, we provide a comprehensive summary on the types of nanoparticle systems used as nanocarriers, highlight the current use of nanocarriers in recombinant DNA and RNAi molecules delivery, and the current landscape of gene-based nanomedicine-ranging from diagnosis to therapeutics. Finally, we briefly discuss the biosafety concerns and limitations in the preclinical and clinical development of nanoparticle gene systems.

Selective tropism of liver stem cells to hepatocellular carcinoma in vivo

AIM: To investigate the selective tropism of liver stem cells to hepatocellular carcinoma (HCC) in an animal model and its feasibility as a vector to deliver therapeutic genes for targeted therapy of HCC.

METHODS: WB-F344, a kind of rat liver stem cell, was infected with recombinant virus to establish a cell line with stable, high-level expressing enhanced green fluorescent protein (EGFP). An animal model of HCC in Wistar rats was established by implanting HCC cells (CBRH7919) combined with an immunosuppressive drug. EGFP labeled liver stem cells were injected into caudal veins of the animals and distribution was observed at different time points after injection. SDF-1 and c-kit expression in non-tumor liver and tumor tissue were analysed by immunohistochemistry for the relationshiop between the expression and migration of liver stem cells. Furthermore, hepatic stem cells were injected via the portal vein, hepatic artery, caudal vein, or directly into the pericancerous liver tissue, respectively, and effects on migration, localization, and proliferation of the hepatic stem cells within the tumor tissue were observed and analyzed.

RESULTS: Recombinant adenovirus could deliver the EGFP gene to hepatic stem cells. A new stem cell line, named WB-EGFP, was established that stably expressed EGFP. WB-EGFP cells still showed selective tropism towards HCC and EGFP expression was stable in vivo. According to immunohistochemistry results, SDF-1 may not be related to the mechanisms of tropism of hepatic stem cells. Different application sites affected the distribution of liver stem cells. Injection via the portal vein was superior with regard to selective migration, localization, and proliferation of the hepatic stem cells within the tumor tissue.

CONCLUSION: Liver stem cells have the biological behavior of selective migration to HCC in vivo and they could localize and proliferate within HCC tissue stably expressing the target gene. Liver stem cells are a potential tool for a targeted gene therapy of HCC.