Emerging approaches and technologies in transplantation: the potential game changers

High-throughput CRISPR technology: a novel horizon for solid organ transplantation

Organ transplantation is the gold standard therapy for end-stage organ failure. However, the shortage of available grafts and long-term graft dysfunction remain the primary barriers to organ transplantation. Exploring approaches to solve these issues is urgent, and CRISPR/Cas9-based transcriptome editing provides one potential solution. Furthermore, combining CRISPR/Cas9-based gene editing with an ex vivo organ perfusion system would enable pre-implantation transcriptome editing of grafts. How to determine effective intervention targets becomes a new problem. Fortunately, the advent of high-throughput CRISPR screening has dramatically accelerated the effective targets. This review summarizes the current advancements, utilization, and workflow of CRISPR screening in various immune and non-immune cells. It also discusses the ongoing applications of CRISPR/Cas-based gene editing in transplantation and the prospective applications of CRISPR screening in solid organ transplantation.

Neonatal-Tissue-Derived Extracellular Vesicle Therapy (NEXT): A Potent Strategy for Precision Regenerative Medicine

Extracellular vesicle (EV)-based therapies have emerged as a promising means in regenerative medicine. However, the conventional EV therapy strategy displays some limitations, such as inefficient EV production and lack of tissue-specific repair effects. Here, it is reported that neonatal-tissue-derived EV therapy (NEXT) is a potent strategy for precision tissue repair. In brief, large amounts of EVs with higher yield/purity can be readily isolated from desired tissues with less production time/cost compared to the conventional cell-culture-based method. Moreover, source factors, such as age and tissue type, can affect the repair efficacy of such tissue-derived EVs in different tissue injury models (skin wounds and acute kidney injury), and neonatal-tissue-derived EVs show superior tissue repair potency compared with adult-tissue-derived EVs. Different age- or tissue-type-derived EVs have distinct composition (e.g., protein) signatures that are likely due to the diverse metabolic patterns of the donor tissues, which may contribute to the specific repair action modes of NEXT in different types of tissue injury. Furthermore, neonatal-tissue-derived EVs can be incorporated with bioactive materials for advanced tissue repair. This study highlights that the NEXT strategy may provide a new avenue for precision tissue repair in many types of tissue injury.

Nanoparticle-Based Interventions for Liver Transplantation

Liver transplantation is the only treatment for hepatic insufficiency as a result of acute and chronic liver injuries/pathologies that fail to recover. Unfortunately, there remains an enormous and growing gap between organ supply and demand. Although recipients on the liver transplantation waitlist have significantly higher mortality, livers are often not allocated because they are (i) classified as extended criteria or marginal livers and (ii) subjected to longer cold preservation time (>6 h) with a direct correlation of poor outcomes with longer cold ischemia. Downregulating the recipient's innate immune response to successfully tolerate a graft having longer cold ischemia times or ischemia-reperfusion injury through induction of immune tolerance in the graft and the host would significantly improve organ utilization and post-transplant outcomes. Broadly, technologies proposed for development aim to extend the life of the transplanted liver through post-transplant or recipient conditioning. In this review, we focus on the potential benefits of nanotechnology to provide unique pre-transplant grafting and recipient conditioning of extended criteria donor livers using immune tolerance induction and hyperthermic pre-conditioning.

Transitioning of renal transplant pathology from allograft to xenograft and tissue engineering pathology: Are we prepared?

Currently, the most feasible and widely practiced option for patients with end-stage organ failure is the transplantation of part of or whole organs, either from deceased or living donors. However, organ shortage has posed and is still posing a big challenge in this field. Newer options being explored are xenografts and engineered/bioengineered tissues/organs. Already small steps have been taken in this direction and sooner or later, these will become a norm in this field. However, these developments will pose different challenges for the diagnosis and management of problems as compared with traditional allografts. The approach to pathologic diagnosis of dysfunction in these settings will likely be significantly different. Thus, there is a need to increase awareness and prepare transplant diagnosticians to meet this future challenge in the field of xenotransplantation/ regenerative medicine. This review will focus on the current status of transplant pathology and how it will be changed in the future with the emerging scenario of routine xenotransplantation.

Into the multi-omics era: Progress of T cells profiling in the context of solid organ transplantation

T cells are the common type of lymphocyte to mediate allograft rejection, remaining long-term allograft survival impeditive. However, the heterogeneity of T cells, in terms of differentiation and activation status, the effector function, and highly diverse T cell receptors (TCRs) have thus precluded us from tracking these T cells and thereby comprehending their fate in recipients due to the limitations of traditional detection approaches. Recently, with the widespread development of single-cell techniques, the identification and characterization of T cells have been performed at single-cell resolution, which has contributed to a deeper comprehension of T cell heterogeneity by relevant detections in a single cell - such as gene expression, DNA methylation, chromatin accessibility, surface proteins, and TCR. Although these approaches can provide valuable insights into an individual cell independently, a comprehensive understanding can be obtained when applied joint analysis. Multi-omics techniques have been implemented in characterizing T cells in health and disease, including transplantation. This review focuses on the thesis, challenges, and advances in these technologies and highlights their application to the study of alloreactive T cells to improve the understanding of T cell heterogeneity in solid organ transplantation.

Regulatory Considerations for Clinical Trial Applications with CRISPR-Based Medicinal Products

Since first proposed as a new tool for gene targeting and genome editing, CRISPR technology has quickly advanced into the clinical stage. Initial studies highlight the potential for CRISPR-Cas9-mediated therapeutic approaches in human medicine to correct incurable genetic diseases and enhance cell-based therapeutic approaches. While acknowledging the opportunities this technology brings for the treatment of patients with severe diseases, timely development of these innovative medicinal products requires regulatory oversight and adaptation of regulatory requirements to ensure the safety and efficacy of medicinal products based on CRISPR technology. We briefly present the current regulatory framework applicable for CRISPR-Cas-based developments as advanced therapy medicinal products. Moreover, scientific- and regulatory-driven considerations relevant for advancing product development toward clinical trial applications in Germany are highlighted by discussing the key aspects of quality and nonclinical and clinical development requirements.

Nanotechnology in Kidney and Islet Transplantation: An Ongoing, Promising Field

Organ transplantation has evolved rapidly in recent years as a reliable option for patients with end-stage organ failure. However, organ shortage, surgical risks, acute and chronic rejection reactions and long-term immunosuppressive drug applications and their inevitable side effects remain extremely challenging problems. The application of nanotechnology in medicine has proven highly successful and has unique advantages for diagnosing and treating diseases compared to conventional methods. The combination of nanotechnology and transplantation brings a new direction of thinking to transplantation medicine. In this article, we provide an overview of the application and progress of nanotechnology in kidney and islet transplantation, including nanotechnology for renal pre-transplantation preservation, artificial biological islets, organ imaging and drug delivery.

Therapeutic Strategies for Mutant SPAST-Based Hereditary Spastic Paraplegia

Mutations of the SPAST gene that encodes the microtubule-severing enzyme called spastin are the chief cause of Hereditary Spastic Paraplegia. Growing evidence indicates that pathogenic mutations functionally compromise the spastin protein and endow it with toxic gain-of-function properties. With each of these two factors potentially relevant to disease etiology, the present article discusses possible therapeutic strategies that may ameliorate symptoms in patients suffering from SPAST-based Hereditary Spastic Paraplegia, which is usually termed SPG4-HSP.

Advances in single-cell sequencing: insights from organ transplantation

Single-cell RNA sequencing (scRNA-seq) is a comprehensive technical tool to analyze intracellular and intercellular interaction data by whole transcriptional profile analysis. Here, we describe the application in biomedical research, focusing on the immune system during organ transplantation and rejection. Unlike conventional transcriptome analysis, this method provides a full map of multiple cell populations in one specific tissue and presents a dynamic and transient unbiased method to explore the progression of allograft dysfunction, starting from the stress response to final graft failure. This promising sequencing technology remarkably improves individualized organ rejection treatment by identifying decisive cellular subgroups and cell-specific interactions.

Multi-Omics Approach in the Identification of Potential Therapeutic Biomolecule for COVID-19

COVID-19 is caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). It has a disastrous effect on mankind due to the contagious and rapid nature of its spread. Although vaccines for SARS-CoV-2 have been successfully developed, the proven, effective, and specific therapeutic molecules are yet to be identified for the treatment. The repurposing of existing drugs and recognition of new medicines are continuously in progress. Efforts are being made to single out plant-based novel therapeutic compounds. As a result, some of these biomolecules are in their testing phase. During these efforts, the whole-genome sequencing of SARS-CoV-2 has given the direction to explore the omics systems and approaches to overcome this unprecedented health challenge globally. Genome, proteome, and metagenome sequence analyses have helped identify virus nature, thereby assisting in understanding the molecular mechanism, structural understanding, and disease propagation. The multi-omics approaches offer various tools and strategies for identifying potential therapeutic biomolecules for COVID-19 and exploring the plants producing biomolecules that can be used as biopharmaceutical products. This review explores the available multi-omics approaches and their scope to investigate the therapeutic promises of plant-based biomolecules in treating SARS-CoV-2 infection.

Multi-Omics Approach in the Identification of Potential Therapeutic Biomolecule for COVID-19

COVID-19 is caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). It has a disastrous effect on mankind due to the contagious and rapid nature of its spread. Although vaccines for SARS-CoV-2 have been successfully developed, the proven, effective, and specific therapeutic molecules are yet to be identified for the treatment. The repurposing of existing drugs and recognition of new medicines are continuously in progress. Efforts are being made to single out plant-based novel therapeutic compounds. As a result, some of these biomolecules are in their testing phase. During these efforts, the whole-genome sequencing of SARS-CoV-2 has given the direction to explore the omics systems and approaches to overcome this unprecedented health challenge globally. Genome, proteome, and metagenome sequence analyses have helped identify virus nature, thereby assisting in understanding the molecular mechanism, structural understanding, and disease propagation. The multi-omics approaches offer various tools and strategies for identifying potential therapeutic biomolecules for COVID-19 and exploring the plants producing biomolecules that can be used as biopharmaceutical products. This review explores the available multi-omics approaches and their scope to investigate the therapeutic promises of plant-based biomolecules in treating SARS-CoV-2 infection.

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.

Single-cell RNA Sequencing in Immunology

The complex immune system is involved in multiple pathological processes. Single-cell RNA sequencing (scRNA-seq) is able to analyze complex cell mixtures correct to a single cell and single molecule, thus is qualified to analyze immune reactions in several diseases. In recent years, scRNA-seq has been applied in many researching fields and has presented many innovative results. In this review, we intend to provide an overview of single-cell RNA sequencing applications in immunology and a prospect of future directions.

The many shades of macrophages in regulating transplant outcome

The shift of emphasis from short-term to long-term graft outcomes has led to renewed interests in how the innate immune cells regulate transplant survival, an area that is traditionally dominated by T cells in the adaptive system. This shift is driven largely by the limited efficacy of current immunosuppression protocols which primarily target T cells in preventing chronic graft loss, as well as by the rapid advance of basic sciences in the realm of innate immunity. In fact, the innate immune cells have emerged as key players in the allograft response in various models, contributing to both graft rejection and graft acceptance. Here, we focus on the macrophages, highlighting their diversity, plasticity and emerging features in transplant models, as well as recent developments in our studies of diverse subsets of macrophages. We also discuss challenges, unsolved questions, and emerging approaches in therapeutically modulating macrophages in further improvement of transplant outcomes.