Exosomes exhibit high bioavailability, biological stability, targeted specificity, low toxicity, and low immunogenicity in shuttling various bioactive molecules such as proteins, lipids, RNA, and DNA. Natural exosomes, however, have limited production, targeting abilities, and therapeutic efficacy in clinical trials. On the other hand, engineered exosomes have demonstrated long-term circulation, high stability, targeted delivery, and efficient intracellular drug release, garnering significant attention. The engineered exosomes bring new insights into developing next-generation drug delivery systems and show enormous potential in therapeutic applications, such as tumor therapies, diabetes management, cardiovascular disease, and tissue regeneration and repair. In this review, we provide an overview of recent advancements associated with engineered exosomes by focusing on the state-of-the-art strategies for cell engineering and exosome engineering. Exosome isolation methods, including traditional and emerging approaches, are systematically compared along with advancements in characterization methods. Current challenges and future opportunities are further discussed in terms of the preparation and application of engineered exosomes.

Despite recent advances in the field of HSCT, viral infections remain a frequent causeof morbidity and mortality among HSCT recipients. Adoptive transfer of viral specific T cells has been successfully used both as prophylaxis and treatment of viral infections in immunocompromised HSCT recipients. Increasingly, precise risk stratification of HSCT recipients with infectious complications should incorporate not only pretransplant clinical criteria, but milestones of immune reconstitution as well. These factors can better identify those at highest risk of morbidity and mortality and identify a population of HSCT recipients in whom adoptive therapy with viral specific T cells should be considered for either prophylaxis or second line treatment early after inadequate response to first line antiviral therapy. Broadening these approaches to improve outcomes for transplant recipients in countries with limited resources is a major challenge. While the principles of risk stratification can be applied, early detection of viral reactivation as well as treatment is challenging in regions where commercial PCR assays and antiviral agents are not readily available.

BACKGROUND: Current therapies are quite unsuccessful in the management of neuropathic pain. Therefore, considering the inhibitory characteristics of GABA mediators, the present systematic review and meta-analysis aimed to determine the efficacy of GABAergic neural precursor cells on neuropathic pain management.
METHODS: Search was conducted on Medline, Embase, Scopus, and Web of Science databases. A search strategy was designed based on the keywords related to GABAergic cells combined with neuropathic pain. The outcomes were allodynia and hyperalgesia. The results were reported as a pooled standardized mean difference (SMD) with a 95% confidence interval (95% CI).
RESULTS: Data of 13 studies were analyzed in the present meta-analysis. The results showed that administration of GABAergic cells improved allodynia (SMD = 1.79; 95% CI: 0.87, 271; P < 0.001) and hyperalgesia (SMD = 1.29; 95% CI: 0.26, 2.32; P = 0.019). Moreover, the analyses demonstrated that the efficacy of GABAergic cells in the management of allodynia and hyperalgesia is only observed in rats. Also, only genetically modified cells are effective in improving both of allodynia, and hyperalgesia.
CONCLUSIONS: A moderate level of pre-clinical evidence showed that transplantation of genetically-modified GABAergic cells is effective in the management of neuropathic pain. However, it seems that the transplantation efficacy of these cells is only statistically significant in improving pain symptoms in rats. Hence, caution should be exercised regarding the generalizability and the translation of the findings from rats and mice studies to large animal studies and clinical trials.

Tumors remain a health concern worldwide, and gene therapy is a useful approach for treating tumors. The Clustered regulatory interspaced short palindromic repeat (CRISPR) system, an efficient and robust gene-editing system originating from bacteria, serves as an important tool in gene therapy. In this review, we briefly summarize the usage of CRISPR (including in gene knockout and gene knock-in applications) and the CRISPRa system in tumor therapy, including its delivery approaches and the general fields in which it has been applied. We summarize the application of the CRISPR system in tumor therapy in two aspects: its application in tumor cell modification and its application in drug engineering. This review also summarizes the advantages and challenges of using the CRISPR system in tumor therapy.

Producing \'designer cells\' with specific functions is potentially feasible in the near future. Recent developments, including whole-cell models, genome design algorithms and gene editing tools, have advanced the possibility of combining biological research and mathematical modelling to further understand and better design cellular processes. In this review, we will explore computational and experimental approaches used for metabolic and genome design. We will highlight the relevance of modelling in this process, and challenges associated with the generation of quantitative predictions about cell behaviour as a whole: although many cellular processes are well understood at the subsystem level, it has proved a hugely complex task to integrate separate components together to model and study an entire cell. We explore these developments, highlighting where computational design algorithms compensate for missing cellular information and underlining where computational models can complement and reduce lab experimentation. We will examine issues and illuminate the next steps for genome engineering.

Skin wounds have significant morbidity and mortality rates associated. This is explained by the limited effectiveness of the currently available treatments, which in some cases do not allow the reestablishment of the structure and functions of the damaged skin, leading to wound infection and dehydration. These drawbacks may have an impact on the healing process and ultimately prompt patients\' death. For this reason, researchers are currently developing new wound dressings that enhance skin regeneration. Among them, electrospun polymeric nanofibres have been regarded as promising tools for improving skin regeneration due to their structural similarity with the extracellular matrix of normal skin, capacity to promote cell growth and proliferation and bactericidal activity as well as suitability to deliver bioactive molecules to the wound site. In this review, an overview of the recent studies concerning the production and evaluation of electrospun polymeric nanofibrous membranes for skin regenerative purposes is provided. Moreover, the current challenges and future perspectives of electrospun nanofibrous membranes suitable for this biomedical application are highlighted.

CHO cells are the most prevalent platform for modern bio-therapeutic production. Currently, there are several CHO cell lines used in bioproduction with distinct characteristics and unique genotypes and phenotypes. These differences limit advances in productivity and quality that can be achieved by the most common approaches to bioprocess optimization and cell line engineering. Incorporating omics-based approaches into current bioproduction processes will complement traditional methodologies to maximize gains from CHO engineering and bioprocess improvements. In order to highlight the utility of omics technologies in CHO bioproduction, the authors discuss current applications as well as limitations of genomics, transcriptomics, proteomics, metabolomics, lipidomics, fluxomics, glycomics, and multi-omics approaches and the potential they hold for the future of bioproduction. Multiple omics approaches are currently being used to improve CHO bioprocesses; however, the application of these technologies is still limited. As more CHO-omic datasets become available and integrated into systems models, the authors expect significant gains in product yield and quality. While individual omics technologies provide incremental improvements in bioproduction, the authors will likely see the most significant gains by applying multi-omics and systems biology approaches to individual CHO cell lines.

Adipose-derived stem cells (ADSCs) are easily obtained and expanded, and have emerged as a novel source of adult stem cells for the treatment of cardiovascular diseases. These cells have been shown to have the capability of differentiating into cardiomyocytes, vascular smooth muscle cells, and endothelial cells. Furthermore, ADSCs secrete a series of paracrine factors to promote neovascularization, reduce apoptosis, and inhibit fibrosis, which contributes to cardiac regeneration. As a novel therapy in the regenerative field, ADSCs still face various limitations, such as low survival and engraftment. Thus, engineering and pharmacological studies have been conducted to solve these problems. Investigations have moved into phase I and II clinical trials examining the safety and efficacy of ADSCs in the setting of myocardial infarction. In this review, we discuss the differentiation and paracrine functions of ADSCs, the strategies promoting their therapeutic efficacy, and their clinical usage.

Several diseases are caused by missing or defective synthesis of proteins due to genetic or acquired disorders. In recent years, in vitro transcribed (IVT) messenger RNA (mRNA)-based therapy for de novo protein expression in cells has increased in importance. Thereby, desired proteins can be produced in cells by exogenous delivery of IVT mRNA, which does not integrate into the host genome and results in transient production of target proteins. Due to the lack of genomic integration, the risk of mutation and tumor development is minimized. Different approaches using IVT mRNA have been applied to alter the expression profiles of cells by the production of proteins. IVT mRNAs encoding transcription factors have led to the highly efficient induction of pluripotency in somatic cells and generated induced pluripotent stem cells that are free of viral vector components. Furthermore, specific IVT mRNA cocktails containing more than one specific IVT mRNA can be used to directly induce the differentiation into a desired cell type. In theory, every desired mRNA can be produced in vitro and used to enable extrinsic biosynthesis of target proteins in each cell type. Cells can be engineered by IVT mRNA to express antigens on dendritic cells for vaccination and tumor treatment, surface receptors on stem cells for increased homing to distinct areas, and to produce industrial grade human growth factors. In this review, we focus on the progress and challenges in mRNA-based cell engineering approaches. Stem Cells 2017;35:68-79.

Regenerative medicine (RM) is a popular term for a field of scientific and medical research. There is not one universally accepted definition of RM, but it is generally taken to mean the translation of multidisciplinary biology and engineering science into therapeutic approaches to regenerate, replace, or repair tissues and organs. RM products have the potential to provide treatments for a number of unmet needs but have substantial scientific and regulatory challenges that need to be addressed for this potential to be fully realized. FDA has established formal regulatory definitions for biologics, medical devices, and combination products, as well as human cells and tissues. Regenerative medicine products regulated by FDA are classified on the basis of these definitions, and the classification forms the basis for determining the regulatory requirements to each specific product. FDA regulations are generally written to allow the agency flexibility to accommodate new scientific questions raised by novel and evolving technologies. FDA efforts to facilitate product development in this novel and promising area include working with individual sponsors, interacting with the scientific and industry communities, participating in standards development, and developing policy and guidance.
CONCLUSIONS: Regenerative medicine is generally taken to mean the translation of multidisciplinary biology and engineering science into therapeutic approaches to regenerate, replace, or repair tissues and organs. This article provides an overview of the efforts of the U.S. Food and Drug Administration (FDA) to facilitate product development in the field commonly known was regenerative medicine. It provides an introduction to the processes by which FDA works with individual sponsors, interacts with the scientific and industry communities, participates in standards development, and develops formal FDA policy and guidance.