Therapeutic cell engineering: designing programmable synthetic genetic circuits in mammalian cells

Cell therapy approaches that employ engineered mammalian cells for on-demand production of therapeutic agents in the patient's body are moving beyond proof-of-concept in translational medicine. The therapeutic cells can be customized to sense user-defined signals, process them, and respond in a programmable and predictable way. In this paper, we introduce the available tools and strategies employed to design therapeutic cells. Then, various approaches to control cell behaviors, including open-loop and closed-loop systems, are discussed. We also highlight therapeutic applications of engineered cells for early diagnosis and treatment of various diseases in the clinic and in experimental disease models. Finally, we consider emerging technologies such as digital devices and their potential for incorporation into future cell-based therapies.

Expansion and characterization of cells from surgically removed intervertebral disc fragments in xenogen-free medium

Low back pain due to degeneration of intervertebral disc (IVD) is a major health problem resulting insignificant disability as well as adding to the economic burden. Discectomy is a very common procedure doneworldwide to relieve this pain. At present all the surgically removed disc tissue is mostly discarded. However,there are reports that state that progenitor cells in the IVD can be grown ex vivo and have the potential to beused for IVD repair and regeneration. We report here that viable cells can be harvested from surgicallyremoved, herniated disc tissue and can be potentially used in cell based therapy. Further, we have successfullyreplaced xenogenic supplements such as foetal bovine serum with either autologous serum or human plateletlysate for culturing IVD cells from patient’s surgically removed disc tissue, without loss of any cell characteristics, including cell surface markers, growth factor secretion in the conditioned medium and osteogenic andchondrogenic differentiation potential in vitro. The present work will not only contribute to overcoming someof the major barriers in carrying out human clinical trials, but also provide a cheap, alternate source of proteinsand growth factors for growing IVD cells ex vivo for therapy

Human Induced Pluripotent Stem Cells: Clinical Significance and Applications in Neurologic Diseases

The generation of human induced pluripotent stem cells (iPSCs) from somatic cells using gene transfer opens new areas for precision medicine with personalized cell therapy and encourages the discovery of essential platforms for targeted drug development. iPSCs retain the genome of the donor, may regenerate indefinitely, and undergo differentiation into virtually any cell type of interest using a range of published protocols. There has been enormous interest among researchers regarding the application of iPSC technology to regenerative medicine and human disease modeling, in particular, modeling of neurologic diseases using patient-specific iPSCs. For instance, Parkinson’s disease, Alzheimer’s disease, and spinal cord injuries may be treated with iPSC therapy or replacement tissues obtained from iPSCs. In this review, we discuss the work so far on generation and characterization of iPSCs and focus on recent advances in the use of human iPSCs in clinical setting.

Stem Cell-Based Therapies for Liver Diseases: An Overview and Update

BACKGROUND: Liver disease is one of the top causes of death globally. Although liver transplantation is a very effective treatment strategy, the shortage of available donor organs, waiting list mortality, and high costs of surgery remain huge problems. Stem cells are undifferentiated cells that can differentiate into a variety of cell types. Scientists are exploring the possibilities of generating hepatocytes from stem cells as an alternative for the treatment of liver diseases. METHODS: In this review, we summarized the updated researches in the field of stem cell-based therapies for liver diseases as well as the current challenges and future expectations for a successful cell-based liver therapy. RESULTS: Several cell types have been investigated for liver regeneration, such as embryonic stem cells, induced pluripotent stem cells, liver stem cells, mesenchymal stem cells, and hematopoietic stem cells. In vitro and in vivo studies have demonstrated that stem cells are promising cell sources for the liver regeneration. CONCLUSION: Stem cell-based therapy could be a promising therapeutic method for patients with end-stage liver disease, which may alleviate the need for liver transplantation in the future.

Preface for special issue on bioengineering and human health (2019) / 生物工程学报

Human health is the foundation of human survival and development. It is an important objective of sustainable development to enhance human health level. With the development of science and technology, bioengineering, as an interdisciplinary biological technology, is becoming the key driver of these goals. This special issue reviewed and discussed the recent progress and future perspectives of bioengineering technologies in the biomedical applications from the aspects of engineering design, disease diagnosis, gene- and cell-based therapies. We hope this special issue could provide valuable references for promoting bioengineering technologies used for the healthcare applications.

Human Induced Pluripotent Stem Cells: Clinical Significance and Applications in Neurologic Diseases

The generation of human induced pluripotent stem cells (iPSCs) from somatic cells using gene transfer opens new areas for precision medicine with personalized cell therapy and encourages the discovery of essential platforms for targeted drug development. iPSCs retain the genome of the donor, may regenerate indefinitely, and undergo differentiation into virtually any cell type of interest using a range of published protocols. There has been enormous interest among researchers regarding the application of iPSC technology to regenerative medicine and human disease modeling, in particular, modeling of neurologic diseases using patient-specific iPSCs. For instance, Parkinson’s disease, Alzheimer’s disease, and spinal cord injuries may be treated with iPSC therapy or replacement tissues obtained from iPSCs. In this review, we discuss the work so far on generation and characterization of iPSCs and focus on recent advances in the use of human iPSCs in clinical setting.

Glial Cell Line-derived Neurotrophic Factor-overexpressing Human Neural Stem/Progenitor Cells Enhance Therapeutic Efficiency in Rat with Traumatic Spinal Cord Injury

Spinal cord injury (SCI) causes axonal damage and demyelination, neural cell death, and comprehensive tissue loss, resulting in devastating neurological dysfunction. Neural stem/progenitor cell (NSPCs) transplantation provides therapeutic benefits for neural repair in SCI, and glial cell line-derived neurotrophic factor (GDNF) has been uncovered to have capability of stimulating axonal regeneration and remyelination after SCI. In this study, to evaluate whether GDNF would augment therapeutic effects of NSPCs for SCI, GDNF-encoding or mock adenoviral vector-transduced human NSPCs (GDNF-or Mock-hNSPCs) were transplanted into the injured thoracic spinal cords of rats at 7 days after SCI. Grafted GDNF-hNSPCs showed robust engraftment, long-term survival, an extensive distribution, and increased differentiation into neurons and oligodendroglial cells. Compared with Mock-hNSPC- and vehicle-injected groups, transplantation of GDNF-hNSPCs significantly reduced lesion volume and glial scar formation, promoted neurite outgrowth, axonal regeneration and myelination, increased Schwann cell migration that contributed to the myelin repair, and improved locomotor recovery. In addition, tract tracing demonstrated that transplantation of GDNF-hNSPCs reduced significantly axonal dieback of the dorsal corticospinal tract (dCST), and increased the levels of dCST collaterals, propriospinal neurons (PSNs), and contacts between dCST collaterals and PSNs in the cervical enlargement over that of the controls. Finally grafted GDNF-hNSPCs substantially reversed the increased expression of voltage-gated sodium channels and neuropeptide Y, and elevated expression of GABA in the injured spinal cord, which are involved in the attenuation of neuropathic pain after SCI. These findings suggest that implantation of GDNF-hNSPCs enhances therapeutic efficiency of hNSPCs-based cell therapy for SCI.

Development of New Preventive and Therapeutic Vaccines for Tuberculosis

Tuberculosis (TB) is a contagious disease that has been responsible for the death of one billion people in the last 200 years. Until now, the only vaccine approved for the prevention of TB is Bacillus Calmette-Guérin (BCG), which is prepared by attenuating Mycobacterium bovis. However, one of the limitations of BCG is that its preventive effect against pulmonary TB varies from person to person. Therefore, there arises a need for a new TB vaccine to replace or supplement BCG. In this review, we have summarized the findings of current clinical trials on preventive and therapeutic TB vaccine candidates. In addition, we have discussed a novel vaccination approach using the cell-based vaccine presenting early secretory antigenic target-6 (ESAT-6), which is a potent immunogenic antigen. The role of ESAT-6 in hosts has also been described.

Research progress of stem cell-derived RPE cell transplantation therapy for retinal degenerative diseases / 国际眼科杂志(Guoji Yanke Zazhi)

·Age - related macular degeneration ( ARMD ) and Stargardt's macular dystrophy ( SMD ) are two kinds of degenerative retinal diseases that respectively lead to irreversible vision loss of the elderly and juvenile population. However, the severe visual impairment in dry ARMD and SMD remains untreatable. In recent years, with the advancement of stem cell technology, stem cell-derived RPE cell transplantation therapy of retinal degeneration has become new research hotspot and direction. This article reviewed the progress of stem cell based approaches for treating retinal degenerative diseases and discussed the prospect and challenges in this field.

Effects of Canine and Murine Mesenchymal Stromal Cell Transplantation on Peripheral Nerve Regeneration

BACKGROUND AND OBJECTIVES: Maintaining a permissive microenvironment is essential for adequate nerve regeneration. Cell-based therapy has the potential based cell replacement and promotion of axonal growth. The adipose tissue derived mesenchymal stromal cells (Ad-MSC) attract interest because neuroregenerative and anti-inflammatory properties. The aim of this study was to evaluate the effects of canine and murine Ad-MSC transplantation on the sciatic nerve regeneration. METHODS: Forty Wistar rats were divided randomly into: control group - CG (n=8); denervated group - DG (n=8); decellularized vein group - VG (n=8); decellularized vein+canine MSC–cMSC (n=8); descellularized vein+murine MSC–mMSC (n=8). After 10-mm nerve gap, the tubulation technique was performed with decellularized vein filled with 10⁶ MSC labeled with quantum dots (Qtracker 665®). The sciatic nerve functional index (SFI) and electroneuromyography (ENMG) measurements were carried and morphometric and immunohistochemistry analysis of the tissue. RESULTS: The SFI values were higher in the cMSC and mMSC groups at day 27 (p<0.020) and day 35 (p<0.011). The ENMG analysis also revealed better results in the mMSC group. Density, number, and total area of the fibers were increased in the mMSC and cMSC groups. Brain-derived neurotrophic factor BDNF and S-100 protein positive immunoreactivity showed a higher expression for both in the nerve of the mMSC and cMSC groups. The MSC labeled with quantum dots were detected at day 35, indicating neuronal survival long after the nerve damage. CONCLUSIONS: Murine and canine Ad-MSC associated with decellularized vein scaffold had positive effects on sciatic nerve regeneration in rats.

Research progress of mammalian synthetic biology in biomedical field / 生物工程学报

Although still in its infant stage, synthetic biology has achieved remarkable development and progress during the past decade. Synthetic biology applies engineering principles to design and construct gene circuits uploaded into living cells or organisms to perform novel or improved functions, and it has been widely used in many fields. In this review, we describe the recent advances of mammalian synthetic biology for the treatment of diseases. We introduce common tools and design principles of synthetic gene circuits, and then we demonstrate open-loop gene circuits induced by different trigger molecules used in disease diagnosis and close-loop gene circuits used for biomedical applications. Finally, we discuss the perspectives and potential challenges of synthetic biology for clinical applications.

Artificial gametes from stem cells / 대한생식의학회지

The generation of artificial gametes is a real challenge for the scientific community today. In vitro development of human eggs and sperm will pave the way for the understanding of the complex process of human gametogenesis and will provide with human gametes for the study of infertility and the onset of some inherited disorders. However, the great promise of artificial gametes resides in their future application on reproductive treatments for all these people wishing to have genetically related children and for which gamete donation is now their unique option of parenthood. This is the case of infertile patients devoid of suitable gametes, same sex couples, singles and those fertile couples in a high risk of transmitting serious diseases to their progeny. In the search of the best method to obtain artificial gametes, many researchers have successfully obtained human germ cell-like cells from stem cells at different stages of differentiation. In the near future, this field will evolve to new methods providing not only viable but also functional and safe artificial germ cells. These artificial sperm and eggs should be able to recapitulate all the genetic and epigenetic processes needed for the correct gametogenesis, fertilization and embryogenesis leading to the birth of a healthy and fertile newborn.

A mini review on the basic knowledge on tendon: revisiting the normal & injured tendon

Tendon is a dense connective tissue that connects muscle to bone. Tendon can adapt to mechanical forces passing across it, through a reciprocal relationship between its cellular components (tenocytes and tenoblasts) and the extracellular matrix (ECM). In early development, the formation of scleraxis-expressing tendon progenitor population in the sclerotome is induced by a fibroblast growth factor signal secreted by the myotome. Tendon injury has been defined as a loss of cells or ECM caused by trauma. It represents a failure of cells and matrix adaptation to mechanical loading. Injury initiates attempts of tendon to repair itself, which has been defined as replacement of damaged or lost cells and ECM by new cells or new matrices. Tendon healing generally consists of four different phases: the inflammatory, proliferation, differentiation and remodelling phases. Clinically, tendons are repaired with a variety of surgical techniques, which show various degrees of success. In order to improve the conventional tendon repair methods, current tendon tissue engineering aims to investigate a repair method which can restore tissue defects with living cells, or cell based therapy. Advances in tissue engineering techniques would potentially yield to a cell-based product that could regenerate functional tendon tissue.

Transforming ocular surface stem cell research into successful clinical practice.

It has only been a quarter of a century since the discovery of adult stem cells at the human corneo-scleral limbus. These limbal stem cells are responsible for generating a constant and unending supply of corneal epithelial cells throughout life, thus maintaining a stable and uniformly refractive corneal surface. Establishing this hitherto unknown association between ocular surface disease and limbal dysfunction helped usher in therapeutic approaches that successfully addressed blinding conditions such as ocular burns, which were previously considered incurable. Subsequent advances in ocular surface biology through basic science research have translated into innovations that have made the surgical technique of limbal stem cell transplantation simpler and more predictable. This review recapitulates the basic biology of the limbus and the rationale and principles of limbal stem cell transplantation in ocular surface disease. An evidence-based algorithm is presented, which is tailored to clinical considerations such as laterality of affl iction, severity of limbal damage and concurrent need for other procedures. Additionally, novel fi ndings in the form of factors infl uencing the survival and function of limbal stem cells aft er transplantation and the possibility of substituting limbal cells with epithelial stem cells of other lineages is also discussed. Finally this review focuses on the future directions in which both basic science and clinical research in this fi eld is headed.

Therapeutic effect of adipose-derived mesenchymal stem cells on radiation enteritis / 中华放射医学与防护杂志

Objective To evaluate the therapeutic effect of adipose-derived mesenchymal stem cells on radiation enteritis.Methods A total of 52 male Sprague-Dawley rats were used in the present study.Herein,46 rats were randomly selected and irradiated with a dose of 15 Gy at their abdomens.Two hours post-irradiation,23 rats were randomly selected and infused intraperitoneally with adipose-derived mesenchymal stem cells in passage 6 from young-female donor.The other 23 rats were intraperitoneally infused with PBS.The rest 6 rats were set as normal control.During the first 10 days post-irradiation,peripheral blood-samples from irradiated rats were harvested for testing the levels of IL-10 in serum using ELISA assay.Additionally,after isolating the thymic cells and peripheral blood mononuclear cells,the percentages of CD4/CD25/Foxp(3)-positive regulatory T cells in thymus and peripheral blood were tested by flow-cytometry.Finally,infiltration of inflammatory cells and deposition of collagens within irradiated small intestine were analyzed by H&E staining and Masson Trichrome staining,respectively.Based on the MPO-immunohistochemistry staining,the type of infiltrated cells was identified.The Kaplan-Meier method was used for analyzing the survival rate of irradiated rats.Results During a period of 30 days post-irradiation,the irradiated rats receiving adipose-derived mesenchymal stem cells survived longer than those receiving PBS (t =4.53,P ＜ 0.05).Compared to the irradiated rats with PBS-treatment,adipose-derived mesenchymal stem cells could elevate the level of IL-10 in serum (7 d:t =13.93,P ＜ 0.05) and increase the percentages of CD4/CD25/Foxp(3)-positive regulatory T cells in both peripheral blood (3.5 d:t =7.72,7 d:t=11.11,10 d:t =6.99,P ＜0.05) and thymus (7 d:t =16.17,10 d:t =12.12,P＜ 0.05).Moreover,infiltration of inflammatory cells and deposition of collagens within irradiated small intestine were mitigated by adipose-derived mesenchymal stem cells.Conclusions Adipose-derived mesenchymal stem cells were capable of curing radiation enteritis.

Cellular mechanisms of emerging applications of mesenchymal stem cells

Mesenchymal stem cells (MSC) are multipotent, self-renewing cells that can be found mainly in the bone marrow, and other post-natal organs and tissues. The ease of isolation and expansion, together with the immunomodulatory properties and their capability to migrate to sites of infl ammation and tumours make them a suitable candidate for therapeutic use in the clinical settings. We review here the cellular mechanisms underlying the emerging applications of MSC in various fi elds.

Neurorestoration Induced by Mesenchymal Stem Cells: Potential Therapeutic Mechanisms for Clinical Trials

Stem cells are emerging as therapeutic candidates in a variety of diseases because of their multipotent capacities. Among these, mesenchymal stem cells (MSCs) derived from bone marrow, umbilical cord blood or adipose tissue, comprise a population of cells that exhibit extensive proliferative potential and retain the ability to differentiate into multiple tissue-specific lineage cells including osteoblasts, chondrocytes, and adipocytes. MSCs have also been shown to enhance neurological recovery, although the therapeutic effects seem to be derived from an indirect paracrine effect rather than direct cell replacement. MSCs secrete neurotrophic factors, promote endogenous neurogenesis and angiogenesis, encourage synaptic connection and remyelination of damaged axons, decrease apoptosis, and regulate inflammation primarily through paracrine actions. Accordingly, MSCs may prevail as a promising cell source for cell-based therapy in neurological diseases.

Characterization of human adipose-derived stem cells and expression of chondrogenic genes during induction of cartilage differentiation

OBJECTIVES: Understanding the changes in chondrogenic gene expression that are involved in the differentiation of human adipose-derived stem cells to chondrogenic cells is important prior to using this approach for cartilage repair. The aims of the study were to characterize human adipose-derived stem cells and to examine chondrogenic gene expression after one, two, and three weeks of induction. MATERIALS AND METHODS: Human adipose-derived stem cells at passage 4 were evaluated by flow cytometry to examine the expression of surface markers. These adipose-derived stem cells were tested for adipogenic and osteogenic differentiation capacity. Ribonucleic acid was extracted from the cells for quantitative polymerase chain reaction analysis to determine the expression levels of chondrogenic genes after chondrogenic induction. RESULTS: Human adipose-derived stem cells were strongly positive for the mesenchymal markers CD90, CD73, CD44, CD9, and histocompatibility antigen and successfully differentiated into adipogenic and osteogenic lineages. The human adipose-derived stem cells aggregated and formed a dense matrix after chondrogenic induction. The expression of chondrogenic genes (collagen type II, aggrecan core protein, collagen type XI, COMP, and ELASTIN) was significantly higher after the first week of induction. However, a significantly elevated expression of collagen type X was observed after three weeks of chondrogenic induction. CONCLUSION: Human adipose-derived stem cells retain stem cell characteristics after expansion in culture to passage 4 and serve as a feasible source of cells for cartilage regeneration. Chondrogenesis in human adiposederived stem cells was most prominent after one week of chondrogenic induction.

Molecular Nuclear Cardiac Imaging / 대한핵의학회잡지

Molecular nuclear cardiac imaging has included Tc-99m Annexin imaging to visualize myocardial apoptosis, but is now usually associated with gene therapy and cell-based therapy. Cardiac gene therapy was not successful so far but cardiac reporter gene imaging was made possible using HSV-TK (herpes simplex virus thymidine kinase) and F-18 FHBG (fluoro-hydroxymethylbutyl guanine) or I-124 FIAU (fluoro-deoxyiodo-arabino-furanosyluracil). Gene delivery was performed by needle injection with or without catheter guidance. TK expression did not last longer than 2 weeks in myocardium. Cell-based therapy of ischemic heart or failing heart looks promising, but biodistribution and differentiation of transplanted cells are not known. Reporter genes can be transfected to the stem/progenitor cells and cells containing these genes can be transplanted to the recipients using catheter-based purging or injection. Repeated imaging should be available and if promoter are varied to let express reporter transgenes, cellular (trans) differentiation can be studied. NIS (sodium iodide symporter) or D2R receptor genes are promising in this aspect.