Cell-free Therapy Research Articles

Immunomodulation of MSCs and MSC-Derived Extracellular Vesicles in Osteoarthritis.

Osteoarthritis (OA) has become recognized as a low-grade inflammatory state. Inflammatory infiltration of the synovium by macrophages, T cells, B cells, and other immune cells is often observed in OA patients and plays a key role in the pathogenesis of OA. Hence, orchestrating the local inflammatory microenvironment and tissue regeneration microenvironment is important for the treatment of OA. Mesenchymal stem cells (MSCs) offer the potential for cartilage regeneration owing to their effective immunomodulatory properties and anti-inflammatory abilities. The paracrine effect, mediated by MSC-derived extracellular vehicles (EVs), has recently been suggested as a mechanism for their therapeutic properties. In this review, we summarize the interactions between MSCs or MSC-derived EVs and OA-related immune cells and discuss their therapeutic effects in OA. Additionally, we discuss the potential of MSC-derived EVs as a novel cell-free therapy approach for the clinical treatment of OA.

Ascites management by cell-free concentrated ascites reinfusion therapy during recovery from drug-induced acute liver injury: a case report

BackgroundThe symptoms of drug-induced hepatic injury are manifold; however, the presence of ascites indicates a severe disease condition. The rapid accumulation of ascites is distressing and requires palliative treatment. Because many cases are addressed by repeated large-volume paracentesis, often resulting in impairment due to protein and electrolyte loss, a different approach is required.Case presentationA 61-year-old Japanese man on maintenance dialysis was admitted to our hospital with acute liver injury. Our patient was diagnosed as having drug-induced liver injury due to warfarin or diltiazem, which started immediately after coronary artery bypass grafting 7 months previously. One month after admission, our patient’s hepatic encephalopathy remained grade 1 and his prothrombin time international normalized ratio was maintained at < 1.5. However, the liver was markedly atrophied with massive ascites. Although liver transplantation was desired, he was considered unfit for transplantation because of his renal and cardiac complications. Therefore, we devised a strategy to manage the massive ascites with cell-free concentrated ascites reinfusion therapy while awaiting liver regeneration. At first, cell-free concentrated ascites reinfusion therapy was required frequently because ascites accumulated rapidly. But the fluid retention interval was gradually extended as intended, and cell-free concentrated ascites reinfusion therapy was withdrawn after 8 months. During that time, the size of his liver increased from 1419 cm3 to 1587 cm3 on computed tomography.ConclusionsCell-free concentrated ascites reinfusion therapy is an apheresis therapy in which ascites are collected aseptically by paracentesis, concentrated, and then reinfused intravenously. This treatment has the advantage of preserving nutrition by reusing the fluid. Previously, cell-free concentrated ascites reinfusion therapy was used only for the management of ascites in patients with cirrhosis or carcinomatous peritonitis. This case suggests that palliation and maintenance of nutritional status with cell-free concentrated ascites reinfusion therapy may be useful as an adjunct to liver regeneration in drug-induced hepatic injury.

Fibrous Scaffolds Enhanced the Paracrine Signaling of Mesenchymal Stem Cells for Cartilage Regeneration

Secretome profiles of mesenchymal stem cells (MSCs) are reflective of their local microenvironments and exert an impact on the surrounding cells, eliciting regenerative responses that creates an opportunity for exploiting MSCs towards a cell-free therapy for cartilage repair. The conventional method of culturing MSCs on a tissue culture plate does not provide the physiological microenvironment for optimum secretome production. This study explored the potential of fibrous scaffolds with specific surface topographies in influencing the MSC secretome production and in enhancing the functionality of MSCs and chondrocytes for cartilage repair. Conditioned media generated from MSCs cultured on fibrous scaffolds improved secretome yield and profile that promoted migration, proliferation, chondrogenesis, as well as mitigated inflammation and protected chondrocytes from apoptosis. FAK and ERK signaling were identified as the mechanotransduction pathways to modulate the MSC morphology and its secretome production, which highlighted scaffold fiber orientation as a key design parameter to direct cellular behavior of MSCs and enhance its paracrine functions. This study demonstrates that a fibrous culture platform could be a more efficient approach for improving and fine-tuning the repertoire of MSC secretome for articular cartilage regeneration.

Cell-Based Therapy for Severe COVID-19 Patients: Clinical Trials and Cost-Utility.

The race among countries and companies to develop efficacious vaccines and therapeutics for the COVID-19 is ongoing fast, with many trials underway. Among this, cell-based therapy is focused on moderate to severe phases of COVID-19, and there have been promising outcomes. Mesenchymal stem cells (MSCs) due to their pro/anti-inflammatory and immune-modulatory behavior, Natural Killer (NK) cells thanks to their capacity of lysing virus-infected cells and regulate the resulting immune response, Dendritic cells thanks to immunotherapy and cell-based vaccine engineering, SARS-CoV2-specific T cells due to stimulate and promote the immune system and MSC-derived exosomes because of cell-free therapy and beneficial manufacturing aspects, hold great promises for cell-based therapy applications for treating COVID-19 and similar viral infections. Moreover, recently, an innovative approach to COVID-19 based on engineered human MSC has been introduced, which is continuously evacuated and degraded by the body’s immune system during the antigen recognition process. However, the economic situation of governments and nations, and the cost of therapeutics influence the clinical approaches to manage and exit from this pandemic. This summary describes cell-based clinical trials and the cost-utility aspects of cell therapy. In this regard, limited clinical studies have been reported; while, several clinical trials have been approved for starting phases 2 and 3 of their trials for treating COVID-19 patients with acute respiratory distress syndrome. Regarding the cost of cell therapy, many believe that the high cost of cell-based therapy will decrease substantially. Hence, there are hopes that cellular therapy can be approved soon for the treatment of viral diseases such as COVID-19. Graphical abstract

Mesenchymal Stromal Cell-Derived Extracellular Vesicles: Their Features and Impact on Fibrosis and Myogenesis in Vitro

Extracellular vesicles (EVs) and, particularly, exosomes are becoming a promising material for “cell-free therapy” of many pathologic conditions. In the recent years therapeutic effects of mesenchymal stromal cells (MSCs) have been attributed to their secretory factors, including EVs. In this study we aim to investigate how EVs produced by MSCs of different tissue origin can influence myogenesis and fibrosis–the main processes that accompany skeletal muscle regeneration. Bone marrow, adipose tissue, intact muscle, and injured muscle-derived rat MSCs were obtained and cultured according to standard protocols. EVs were obtained by ultracentrifugation from the MSC-conditioned medium of cell passages 2 and 3. The effects of EVs were estimated on the in vitro models of myogenesis and fibrosis. Samples of isolated EVs contained nano-sized vesicles that carried some exosomal markers. Promyogenic microRNA were found in EVs from bone marrow and muscle MSCs. We found that MSC-derived EVs from all sources significantly increased the number of newly formed myotubes in myoblast culture in vitro and also reduced the number and size of fibrotic nodules in muscle fibroblast culture in vitro. Our results suggest that MSC-derived EVs indeed possess antifibrotic and promyogenic potentials. However, the role of microRNA in these processes is yet to be determined, and the effect of EVs on skeletal muscle regeneration is yet to be tested in vivo.

Exosomes in disease and regeneration: biological functions, diagnostics, and beneficial effects.

Exosomes are a subtype of extracellular vesicles. They range from 30 to 150 nm in diameter and originate from intraluminal vesicles. Exosomes were first identified as the mechanism for releasing unnecessary molecules from reticulocytes as they matured to red blood cells. Since then, exosomes have been shown to be secreted by a broad spectrum of cells and play an important role in the cardiovascular system. Different stimuli are associated with increased exosome release and result in different exosome content. The release of harmful DNA and other molecules via exosomes has been proposed as a mechanism to maintain cellular homeostasis. Because exosomes contain parent cell-specific proteins on the membrane and in the cargo that is delivered to recipient cells, exosomes are potential diagnostic biomarkers of various types of diseases, including cardiovascular disease. As exosomes are readily taken up by other cells, stem cell-derived exosomes have been recognized as a potential cell-free regenerative therapy to repair not only the injured heart but other tissues as well. The objective of this review is to provide an overview of the biological functions of exosomes in heart disease and tissue regeneration. Therefore, state-of-the-art methods for exosome isolation and characterization, as well as approaches to assess exosome functional properties, are reviewed. Investigation of exosomes provides a new approach to the study of disease and biological processes. Exosomes provide a potential "liquid biopsy," as they are present in most, if not all, biological fluids that are released by a wide range of cell types.

Mesenchymal Stem Cell Secretome as an Emerging Cell-Free Alternative for Improving Wound Repair.

The use of mesenchymal stem cells (MSC) for the treatment of cutaneous wounds is currently of enormous interest. However, the broad translation of cell therapies into clinical use is hampered by their efficacy, safety, manufacturing and cost. MSCs release a broad repertoire of trophic factors and immunomodulatory cytokines, referred to as the MSC secretome, that has considerable potential for the treatment of cutaneous wounds as a cell-free therapy. In this review, we outline the current status of MSCs as a treatment for cutaneous wounds and introduce the potential of the MSC secretome as a cell-free alternative for wound repair. We discuss the challenges and provide insights and perspectives for the future development of the MSC secretome as well as identify its potential clinical translation into a therapeutic treatment.

Pulsed focused ultrasound enhances the therapeutic effect of mesenchymal stromal cell-derived extracellular vesicles in acute kidney injury

BackgroundAcute kidney injury (AKI) is characterized by rapid failure of renal function and has no curative therapies. Mesenchymal stromal cell (MSC)-derived extracellular vesicles (EVs) are known to carry therapeutic factors, which have shown promise in regenerative medicine applications, including AKI. However, there remains an unmet need to optimize their therapeutic effect. One potential avenue of optimization lies in pulsed focused ultrasound (pFUS), where tissues-of-interest are treated with sound waves. pFUS has been shown to enhance MSC therapy via increased cell homing, but its effects on cell-free EV therapy remain largely unexplored.MethodsWe combine pFUS pretreatment of the kidney with MSC-derived EV therapy in a mouse model of cisplatin-induced AKI.ResultsEVs significantly improved kidney function, reduced injury markers, mediated increased proliferation, and reduced inflammation and apoptosis. While pFUS did not enhance EV homing to the kidney, the combined treatment resulted in a superior therapeutic effect compared to either treatment alone. We identified several molecular mechanisms underlying this synergistic therapeutic effect, including upregulation of proliferative signaling (MAPK/ERK, PI3K/Akt) and regenerative pathways (eNOS, SIRT3), as well as suppression of inflammation.ConclusionTaken together, pFUS may be a strategy for enhancing the therapeutic efficacy of MSC-derived EV treatment for the treatment of AKI.

Generation of Small RNA-Modulated Exosome Mimetics for Bone Regeneration.

Administration of exosomes is considered an attractive cell-free approach to skeletal repair and pathological disease treatment. However, poor yield for the production technique and unexpected therapeutic efficacy of exosomes have been obstacles to their widespread use in clinical practices. Here, we report an alternative strategy to produce exosome-related vesicles with high yields and improved regenerative capability. An extrusion approach was employed to amass exosome mimetics (EMs) from human mesenchymal stem cells (hMSCs). The collected EMs had a significantly increased proportion of vesicles positive for the exosome-specific CD-63 marker compared with MSC-derived exosomes. EMs were further obtained from genetically modified hMSCs in which expression of noggin, a natural bone morphogenetic protein antagonist, was down-regulated to enhance osteogenic properties of EMs. Moreover, the administration of hMSC-EMs in conjunction with an injectable chitosan hydrogel into mouse nonhealing calvarial defects demonstrated robust bone regeneration. Importantly, mechanistic studies revealed that the enhanced osteogenesis by EMs in which noggin was suppressed was mediated via inhibition of miR-29a. These findings demonstrate the great promise of MSC-mediated EMs and modulation of small RNA signaling for skeletal regeneration and cell-free therapy.

Suppression of inflammation during cell-free concentrated ascites reinfusion therapy using a blood purification device.

In recent years, cell-free concentrated ascites reinfusion therapy has been used to treat patients with malignant ascites. However, concentrated ascites reinfusion therapy involves enrichment and reinfusion of useful proteins and inflammatory cytokines. Therefore, fever is a primary side effect and significant problem for patients with ascites. We removed IL-6, an inflammatory cytokine, by mixing malignant ascites and the hexadecyl group adsorbent from a β2 -microglobulin-adsorbing column (Lixelle S-15). As a result, the hexadecyl group adsorbent did not adsorb the albumin of malignant ascites but adsorbed 43% of IL-6. To investigate the effect of the hexadecyl group adsorbent on hepatocytes, the adsorbed ascites was added to a human hepatoma cell line (HepG2), and the gene expression levels of albumin and serum amyloid A protein were examined. After absorption, ascites showed significantly suppressed serum amyloid A protein expression and significantly increased albumin gene expression compared to before adsorption. Our results suggest that incorporation of Lixelle to filter and concentrate malignant ascites can suppress inflammatory responses and reduce the inhibition of albumin synthesis in the liver after reinfusion.

MOUSE UMBILICAL CORD MESENCHYMAL STEM CELL PARACRINE ALLEVIATES RENAL FIBROSIS IN DIABETIC NEPHROPATHY BY REDUCING MYOFIBROBLAST TRANSDIFFERENTIATION AND CELL PROLIFERATION AND UPREGULATING MMPS IN MESANGIAL CELLS

Special Medicine. Cell Transplantation and Gene Therapy. Transplantation of umbilical cord mesenchymal stem cells (UC-MSCs) is currently considered as a novel therapeutic strategy for diabetic nephropathy (DN). However, the mechanisms by which UC-MSCs ameliorate renal fibrosis in DN are not well understood. Herein, we firstly investigated the therapeutic effects of mouse UC-MSC infusion on kidney structural and functional impairment in streptozotocin (STZ)-induced diabetic mice. We found that the repeated injection with mUC-MSCs alleviates albuminuria, glomerulus injury and fibrosis in DN mouse models. Next, mesangial cells were exposed to 5.6 mM glucose, 30mM glucose or mUC-MSC conditioned medium, and then performed western blotting, immunofluorescence, wound healing assay, and cell proliferation assay to measure extra cellular matrix (ECM) proteins and matrix metalloproteinases (MMPs), myofibroblast transdifferentiation (MFT), and cell proliferation. We demonstrated that mUC-MSC paracrine decreased the deposition of fibronectin and collagen I by inhibiting TGF-β1-triggered MFT and cell proliferation mediated by PI3K/Akt and MAPK signaling pathways, and elevating the levels of MMP2 and MMP9. Importantly, we provided the evidence that the anti-fibrosis role of mU-MSC paracrine in DN might be determined by exosomes shed by MSCs. Together, these findings reveal the mechanisms underlying the therapeutic effects of UC-MSCs on renal fibrosis in DN and provide the evidence for DN cell-free therapy based on UC-MSCs in the future. National Natural Science Foundation of China (no. 81671752, 81471715, 81771827, and 81201171). Natural Science Foundation of Hunan Province, China (no. 2017JJ3423). Hunan Provincial Science and Technology Department major project (no. 2018SK1020). Project of Health and Family Planning Commission of Hunan Province (no. 20160125).

Mesenchymal stem cell-derived exosomes: Toward cell-free therapeutic strategies in regenerative medicine.

Mesenchymal stem cells (MSCs) are multipotent stem cells with marked potential for regenerative medicine because of their strong immunosuppressive and regenerative abilities. The therapeutic effects of MSCs are based in part on their secretion of biologically active factors in extracellular vesicles known as exosomes. Exosomes have a diameter of 30-100 nm and mediate intercellular communication and material exchange. MSC-derived exosomes (MSC-Exos) have potential for cell-free therapy for diseases of, for instance, the kidney, liver, heart, nervous system, and musculoskeletal system. Hence, MSC-Exos are an alternative to MSC-based therapy for regenerative medicine. We review MSC-Exos and their therapeutic potential for a variety of diseases and injuries.

Insight into the proteomic profiling of exosomes secreted by human OM-MSCs reveals a new potential therapy

Mesenchymal stromal cells (MSCs) have been used for the treatment of neuronal injury and neurodegenerative diseases. Their underlying mechanism may involve increased secretion of paracrine factors, which promotes tissue repair. Presently, exosomes have been regarded as important components of paracrine secretion and paracrine factors. MSC exosomes represent a promising opportunity to develop novel cell-free therapy approaches. In this study, exosomes from nasal olfactory mucosa MSCs (OM-MSCs) were extracted and purified using ultracentrifugation, resulting in exosome diameters of 40–130 nm. Similar to other exosomes, OM-MSC exosomes were CD63- and CD81-positive and calnexin-negative. Functionally, OM-MSC exosomes promoted human brain microvascular endothelial cell (HBMEC) proliferation and migration. The present study analyzed the OM-MSC exosome paracrine proteome. A total of 304 exosome-associated proteins were identified by LC–MS/MS, including plasminogen activator inhibitor 1 (SERPINE 1), insulin-like growth factor binding protein family members (IGFBP 4 and 5), epidermal growth factor receptor (EGFR), neurogenic locus notch homolog protein 2 (NOTCH 2), apolipoprotein E (APOE), and heat shock protein HSP90-beta (HSP90AB1). These molecules are known to be important in neurotrophic, angiogenesis, cell growth, differentiation, apoptosis, and inflammation and are highly correlated with the mechanism of tissue repair and neural restoration. These observations may provide a basis for further evaluation of OM-MSC exosome potential as a novel therapeutic modality.

Stemness Potency of Human Gingival Cells-Application in Anticancer Therapies and Clinical Trials.

Gingivae, as the part of periodontium, are involved in tooth support and possess the ability to heal rapidly, without scar formation. Recently, dental tissues have been identified as a potential source of mesenchymal stem cells (MSCs) and several populations of MSCs were isolated from the orofacial region, including gingival mesenchymal stem cells (GMSCs). GMSCs exhibit robust immunomodulatory and differentiation potential and are easily obtainable, which make them promising candidates for cellular therapies. Apart from being tested for application in immunologic- and inflammatory-related disorders and various tissue regeneration, GMSCs promise to be a valuable tool in cancer treatment, especially in tongue squamous cell carcinoma (TSCC) with the use of targeted therapy, since GMSCs are able to selectively migrate towards the cancerous cells both in vitro and in vivo. In addition to their ability to uptake and release anti-neoplastic drugs, GMSCs may be transduced with apoptosis-inducing factors and used for cancer growth inhibition. Moreover, GMSCs, as most mammalian cells, secrete exosomes, which are a subset of extracellular vesicles with a diameter of 40–160 nm, containing DNA, RNA, lipids, metabolites, and proteins. Such GMSCs-derived exosomes may be useful therapeutic tool in cell-free therapy, as well as their culture medium. GMSCs exhibit molecular and stem-cell properties that make them well suited in preclinical and clinical studies.

Mesenchymal Stem Cell-Derived Exosomes for Treatment of Autism Spectrum Disorder.

Recent breakthroughs in the field of stem cell therapy have brought hope to the treatment of mental diseases. Animal experiments and clinical studies have shown that transplantation of mesenchymal stem cells (MSCs) has a positive effect on the treatment of autism spectrum disorder (ASD). However, the therapeutic efficacy of the MSC transplants was primarily associated with the signals and molecules secreted by the MSCs. Exosomes, for example, the secreted organelles from MSCs, carry bioactive molecules of the MSCs that are essential for the therapeutic effects in ASD treatment. This then inspires us to explore the intranasal delivery of MSC exosomes to brain tissues for the treatment of ASD. Exosomes from human umbilical cord mesenchymal stem cells (hUC-MSCs) that efficiently enter the brain tissue through the intranasal route restore the social ability of the mice and correct the repeated stereotyped behaviors and other abnormal phenotypes in the offspring of valproic acid (VPA)-treated mice, which show autism-like symptoms. The therapeutic efficacy can be attributed at least partially to the anti-inflammatory effect of the MSC exosomes. This work thereby reports brain-specific delivery of hUC-MSC exosomes, as a cell-free therapy to relieve autism-related phenotypes, providing a promising direction for the treatment of mental development disorders.

Supramolecular Nanofibers Containing Arginine-Glycine-Aspartate (RGD) Peptides Boost Therapeutic Efficacy of Extracellular Vesicles in Kidney Repair.

Extracellular vesicles (EVs) derived from mesenchymal stem cells (MSC-EVs) have been recognized as a promising cell-free therapy for acute kidney injury (AKI), which avoids safety concerns associated with direct cell engraftment. However, low stability and retention of MSC-EVs have limited their therapeutic efficacy. RGD (Arg-Gly-Asp) peptide binds strongly to integrins, which have been identified on the surface of MSC-EV membranes; yet RGD has not been applied to EV scaffolds to enhance and prolong bioavailability. Here, we developed RGD hydrogels, which we hypothesized could augment MSC-EV efficacy in the treatment of AKI models. In vivo tracking of the labeled EVs revealed that RGD hydrogels increased retention and stability of EVs. Integrin gene knockdown experiments confirmed that EV-hydrogel interaction was mediated by RGD-integrin binding. Upon intrarenal injection into mouse AKI models, EV-RGD hydrogels provided superior rescuing effects to renal function, attenuated histopathological damage, decreased tubular injury, and promoted cell proliferation in early phases of AKI. RGD hydrogels also augmented antifibrotic effects of MSC-EVs in chronic stages. Further analysis revealed that the presence of microRNA let-7a-5p in MSC-EVs served as the mechanism contributing to the reduced cell apoptosis and elevated cell autophagy in AKI. In conclusion, RGD hydrogels facilitated MSC-derived let-7a-5p-containing EVs, improving reparative potential against AKI. This study developed an RGD scaffold to increase the EV integrin-mediated loading and in turn improved therapeutic efficacy in renal repair; therefore this strategy shed light on MSC-EV application as a cell-free treatment for potentiated efficiency.

GMP-compliant sponge-like dressing containing MSC lyo-secretome: Proteomic network of healing in a murine wound model

Chronic wounds account for 3% of total healthcare expenditure of developed countries; thus, innovative therapies, including Mesenchymal Stem Cells (MSCs) end their exosomes are increasingly considered, even if the activity depends on the whole secretome, made of both soluble proteins and extracellular vesicles. In this work, we prove for the first time the in vivo activity of the whole secretome formulated in a sponge-like alginate wound dressing to obtain the controlled release of bioactive substances. The product has been prepared in a public GMP-compliant facility by a scalable process; based on the murine model, treated wounds healed faster than controls without complications or infections. The treatment induced a higher acute inflammatory process in a short time and sustained the proliferative phase by accelerating fibroblast migration, granulation tissue formation, neovascularization and collagen deposition. The efficacy was substantially supported by the agreement between histological and proteomic findings. In addition to functional modules related to proteolysis, complement and coagulation cascades, protein folding and ECM remodeling, in treated skin, emerged the role of specific wound healing related proteins, including Tenascin (Tnc), Decorin (Dcn) and Epidermal growth factor receptor (EGFR). Of note, Decorin and Tenascin were also components of secretome, and network analysis suggests a potential role in regulating EGFR. Although further experiments will be necessary to characterize better the molecular keys induced by treatment, overall, our results confirm the whole secretome efficacy as novel “cell-free therapy”. Also, sponge-like topical dressing containing the whole secretome, GMP- compliant and “ready-off-the-shelf”, may represent a relevant point to facilitate its translation into the clinic.

Chondrocyte-Targeted MicroRNA Delivery by Engineered Exosomes toward a Cell-Free Osteoarthritis Therapy.

Targeted delivery to the diseased cell or tissue is the key to the successful clinical use of nucleic acid drugs. In particular, delivery of microRNA-140 (miRNA-140, miR-140) into chondrocytes across the dense, nonvascular extracellular matrix of cartilage remains a major challenge. Here, we report the chondrocyte-targeting exosomes as vehicles for the delivery of miR-140 into chondrocytes as a new treatment for osteoarthritis (OA). By fusing a chondrocyte-affinity peptide (CAP) with the lysosome-associated membrane glycoprotein 2b protein on the surface of exosomes, we acquire CAP-exosomes that can efficiently encapsulate miR-140, specifically enter, and deliver the cargo into chondrocytes in vitro. CAP-exosomes, in contrast to nontagged exosome vesicles, are retained in the joints after intra-articular injection with minimal diffusion in vivo. CAP-exosomes also deliver miR-140 to deep cartilage regions through the dense mesochondrium, inhibit cartilage-degrading proteases, and alleviate OA progression in a rat model, pointing toward a potential organelle-based, cell-free therapy of OA.

Trends in Salivary Gland Tissue Engineering: From Stem Cells to Secretome and Organoid Bioprinting

Xerostomia or dry mouth are commonly diagnosed in head and neck cancer patients due to salivary gland (SG) epithelial injury after radiotherapy. Regenerative medicine has fetched the opportunity to replace or regenerate the SG epithelia and restore its secretory function. Early adult stem cell transplantation strategies in rodents have recently shown to improve clinical outcomes in radiotherapy-induced xerostomia in Phase 1/2 human trials. Mesenchymal stem cells from adipose tissue are the most promising, although the ones from the labial mucosa, bone marrow, or dental pulp have an attractive therapeutic value after successful findings in ex vivo and in vivo mouse models of SG injury. Emerging approaches using cell-free therapy with cell "extracts", "soups" or secretome components also exhibit favorable outcomes in the same rodent models. When compared to cell-based approaches, extracellular vesicles (EV) from the secretome (i.e., exosomes) can be easily extracted, quantified, and are more stable for long-term storage and use in SG tissue engineering. Additive manufacturing and three-dimensional bioprinting or bioassembly have an important role on generating spheroids or organoids for cell transplantation to ameliorate SG injury. Moreover, organoids can secrete EV, which may have a therapeutic potential worth to explore in future studies. In this review, we will describe the technological advancements and challenges of these different cell-based and cell-free strategies in SG tissue engineering and regeneration. Impact statement Salivary gland (SG)-like innervated epithelial organoids and the secretome produced from stem cells may constitute feasible therapeutic alternatives to regenerate the SG due to their user-friendly, short-lived, consistent, and scalable additive manufacturing processes. Bioprinting such human SG organoids toward in vitro drug discovery may further reduce the incorporation of animal-derived components to the tissue constructs and minimize the use of animal experimentation in SG regeneration. Despite such advancements, transplantation with human adipose-derived mesenchymal stem cells is the only tissue engineering strategy that has reached Phase 1/2 clinical trials and shown to enlarge the serous SG epithelium and improve salivary flow.

Biochemical evaluation of processed ascites in patients undergoing cell-free and concentrated ascites reinfusion therapy.

The biochemical composition of processed ascites is not well researched and may differ among institutions. This prospective study was conducted to evaluate the biochemical characteristics of processed ascites of 11 patients with liver cirrhosis and carcinoma who underwent cell-free and concentrated ascites reinfusion therapy. The ascites due to carcinoma were more acidic and had higher lactate dehydrogenase activity than those due to liver cirrhosis. The ascites due to liver cirrhosis contained a higher amount of immunoglobulin than those due to carcinoma. Immunoglobulin preparations were approximately 2.95% IgG in liver cirrhosis ascites and 2.25% IgG in carcinoma ascites. Moreover, the concern about IgA infusion in the patient with IgA deficiency made it important to identify the source of the ascites. The present study provided fundamental information regarding the safety of cell-free and concentrated ascites reinfusion therapy.