Secretome of human adipose-derived mesenchymal stem cell relieves pain and neuroinflammation independently of the route of administration in experimental osteoarthritis

The iPSC secretome is beneficial for in vitro propagation of primary osteoarthritic chondrocytes cell lines

BACKGROUND

One of the obstacles to autologous chondrocyte implantation (ACI) is obtaining a large quantity of chondrocytes without depletion of their properties. The conditioned medium (CM) from different subpopulations of stem cells (mesenchymal stromal cells (MSC) or induced pluripotent stem cells (iPSC)) could be a gamechanger. MSCs' potential is related to the donor's health and age, which could be omitted when, as a source, iPSCs are used. There is a lack of data regarding their use in the chondrocyte culture expansion. Thus, we wanted to verify whether iPSC-CM could be beneficial for the cell culture of primary chondrocyte cells.

METHODS

We added the iPSC-CMs from GPCCi001-A and ND 41658*H cells to the culture of primary chondrocyte cell lines isolated from OA patients (n = 6) for other two passages. The composition of the CM was evaluated using Luminex technology. Then, we analysed the senescence, proliferation rate and using flow cytometry: viability, distribution of cell cycle phases, production of reactive oxygen species (ROS) and double-strand breaks. The cartilage-related markers were evaluated using Western blot and immunofluorescence. Additionally, a three-dimensional cell culture was used to determine the potential to form cartilage particles.

RESULTS

iPSC-CM increased proliferation and diminished cell ROS production and senescence. CM influenced the cartilage-related protein expression and promoted the growth of cartilage particles. The cell exposed to CM did not lose the ECM proteins, suggesting the chondroprotective effect for prolonged culture time.

CONCLUSION

Our preliminary results suggest a beneficial effect on maintaining chondrocyte biology during in vitro expansion.

Culturing Conditions Dictate the Composition and Pathways Enrichment of Human and Rat Perirenal Adipose-Derived Stromal Cells' Secretomes

Understanding the impact of various culturing strategies on the secretome composition of adipose-derived stromal cells (ASC) enhances their therapeutic potential. This study investigated changes in the secretome of perirenal ASC (prASC) under different conditions: normoxia, cytokine exposure, high glucose, hypoxia, and hypoxia with high glucose. Using mass spectrometry and enrichment clustering analysis, we found that normoxia enriched pathways related to extracellular matrix (ECM) organization, platelet degranulation, and insulin-like growth factor (IGF) transport and uptake. Cytokine exposure influenced metabolism, vascular development, and protein processing pathways. High glucose affected the immune system, metabolic processes, and IGF transport and uptake. Hypoxia impacted immune and metabolic processes and protein processing. Combined hypoxia and high glucose influenced the immune system, IGF transport and uptake, and ECM organization. Our findings highlight the potential of manipulating culturing conditions to produce secretomes with distinct protein and functional profiles, tailoring therapeutic strategies accordingly.

Neuroinflammation in osteoarthritis: From pain to mood disorders

Osteoarthritis (OA) is the most common form of musculoskeletal disease, and its prevalence is increasing due to the aging of the population. Chronic pain is the most burdensome symptom of OA that significantly lowers patients' quality of life, also due to its frequent association with emotional comorbidities, such as anxiety and depression. In recent years, both chronic pain and mood alterations have been linked to the development of neuroinflammation in the peripheral nervous system, spinal cord and supraspinal brain areas. Thus, mechanisms at the basis of the development of the neuroinflammatory process may indicate promising targets for novel treatment for pain and affective comorbidities that accompany OA. In order to assess the key role of neuroinflammation in the maintenance of chronic pain and its potential involvement in development of psychiatric components, the monoiodoacetate (MIA) model of OA in rodents has been used and validated. In the present commentary article, we aim to summarize up-to-date results achieved in this experimental model of OA, focusing on glia activation and cytokine production in the sciatic nerve, dorsal root ganglia (DRGs), spinal cord and brain areas. The association of a neuroinflammatory state with the development of pain and anxiety- and depression-like behaviors are discussed. Results suggest that cells and molecules involved in neuroinflammation may represent novel targets for innovative pharmacological treatments of OA pain and mood comorbidities.

Boosting the therapeutic potential of cell secretome against osteoarthritis: Comparison of cytokine-based priming strategies

The secretome, or conditioned medium (CM), from Mesenchymal Stem/stromal Cells (MSCs) has recently emerged as a promising cell-free therapeutic against osteoarthritis (OA), capable of promoting cartilage regeneration and immunoregulation. Priming MSCs with 10 ng/ml tumor necrosis factor α (TNFα) and/or 10 ng/ml interleukin 1β (IL-1β) aims at mimicking the pathological milieu of OA joints in order to target their secretion towards a pathology-tailored phenotype. Here we compare the composition of the CM obtained after 24 or 72 h from untreated and cytokine-treated adipose-derived MSCs (ASCs). The 72-hour double-primed CM presents a higher total protein yield, a larger number of extracellular vesicles, and a greater concentration of bioactive lipids, in particular sphingolipids, fatty acids, and eicosanoids. Moreover, the levels of several factors involved in immunomodulation and regeneration, such as TGF-β1, PGE2, and CCL-2, are strongly upregulated. Additionally, the differential profiling of 80 bioactive molecules indicates that primed CM is enriched in immune cell chemotaxis and migration factors. Our results indicate that pre-conditioning ASCs with inflammatory cytokines can modulate the composition of their CM, promoting the release of factors with recognized anti-inflammatory, chondroprotective, and immunoregulatory properties.

Revolutionizing orofacial pain management: the promising potential of stem cell therapy

Orofacial pain remains a significant health issue in the United States. Pain originating from the orofacial region can be composed of a complex array of unique target tissue that contributes to the varying success of pain management. Long-term use of analgesic drugs includes adverse effects such as physical dependence, gastrointestinal bleeding, and incomplete efficacy. The use of mesenchymal stem cells for their pain relieving properties has garnered increased attention. In addition to the preclinical and clinical results showing stem cell analgesia in non-orofacial pain, studies have also shown promising results for orofacial pain treatment. Here we discuss the outcomes of mesenchymal stem cell treatment for pain and compare the properties of stem cells from different tissues of origin. We also discuss the mechanism underlying these analgesic/anti-nociceptive properties, including the role of immune cells and the endogenous opioid system. Lastly, advancements in the methods and procedures to treat patients experiencing orofacial pain with mesenchymal stem cells are also discussed.

Towards standardization of human adipose-derived stromal cells secretomes

The secretome of adipose-derived stromal cells (ASC) is a heterogeneous mixture of components with a beneficial influence on cellular microenvironments. As such, it represents a cell-free alternative in regenerative medicine therapies. Pathophysiological conditions increase the therapeutic capacity of ASC and, with this, the benefits of the secretome. Such conditions can be partially mimicked in vitro by adjusting culturing conditions. Secretomics, the unbiased analysis of a cell secretome by mass spectrometry, is a powerful tool to describe the composition of ASC secretomes. In this proteomics databases review, we compared ASC secretomic studies to retrieve persistently reported proteins resulting from the most explored types of culturing conditions used in research, i.e., exposure to normoxia, hypoxia, or cytokines. Our comparisons identified only eight common proteins within ASC normoxic secretomes, no commonalities within hypoxic ASC secretomes, and only nine within secretomes of ASC exposed to proinflammatory cytokines. Within these, and regardless of the culturing condition that stimulated secretion, a consistent presence of extracellular matrix-related pathways associated with such proteins was identified. Confounders such as donors' age, sex, body mass index, the anatomical area where ASC were harvested, secretome collection method, data description, and how the data is shared with the scientific community are discussed as factors that might explain our outcomes. We conclude that standardization is imperative as the currently available ASC secretomic studies do not facilitate solid conclusions on the therapeutic value of different ASC secretomes.

Supraspinal neuroinflammation and anxio-depressive-like behaviors in young- and older- adult mice with osteoarthritis pain: the effect of morphine

RATIONALE

Asteoarthritis (OA) is a leading cause of chronic pain in the elderly population and is often associated with emotional comorbidities such as anxiety and depression. Despite age is a risk factor for both OA and mood disorders, preclinical studies are mainly conducted in young adult animals.

OBJECTIVES

Here, using young adult (11-week-old) and older adult (20-month-old) mice, we evaluate in a monosodium-iodoacetate-(MIA)-induced OA model the development of anxio-depressive-like behaviors and whether brain neuroinflammation may underlie the observed changes. We also test whether an effective pain treatment may prevent behavioral and biochemical alterations.

METHODS

Mechanical allodynia was monitored throughout the experimental protocol, while at the end of protocol (14 days), anxio-depressive-like behaviors and cognitive dysfunction were assessed. Neuroinflammatory condition was evaluated in prefrontal cortex, hippocampus and hypothalamus. Serum IFNγ levels were also measured. Moreover, we test the efficacy of a 1-week treatment with morphine (2.5 mg/kg) on pain, mood alterations and neuroinflammation.

RESULTS

We observed that young adult and older adult controls (CTRs) mice had comparable allodynic thresholds and developed similar allodynia after MIA injection. Older adult CTRs were characterized by altered behavior in the tests used to assess the presence of depression and cognitive impairment and by elevated neuroinflammatory markers in brain areas compared to younger ones. The presence of pain induced depressive-like behavior and neuroinflammation in adult young mice, anxiety-like behavior in both age groups and worsened neuroinflammation in older adult mice. Morphine treatment counteracted pain, anxio-depressive behaviors and neuroinflammatory activation in both young adult and older adult mice.

CONCLUSIONS

Here, we demonstrated that the presence of chronic pain in young adult mice induces mood alterations and supraspinal biochemical changes and aggravates the alterations already evident in older adult animals. A treatment with morphine, counteracting the pain, prevents the development of anxio-depressive disorders and reduces neuroinflammation.

Prokineticin System Is a Pharmacological Target to Counteract Pain and Its Comorbid Mood Alterations in an Osteoarthritis Murine Model

Osteoarthritis (OA) is the most prevalent joint disease associated with chronic pain. OA pain is often accompanied by mood disorders. We addressed the role of the Prokineticin (PK) system in pain and mood alterations in a mice OA model induced with monosodium iodoacetate (MIA). The effect of a PK antagonist (PC1) was compared to that of diclofenac. C57BL/6J male mice injected with MIA in the knee joint were characterized by allodynia, motor deficits, and fatigue. Twenty-eight days after MIA, in the knee joint, we measured high mRNA of PK2 and its receptor PKR1, pro-inflammatory cytokines, and MMP13. At the same time, in the sciatic nerve and spinal cord, we found increased levels of PK2, PKR1, IL-1β, and IL-6. These changes were in the presence of high GFAP and CD11b mRNA in the sciatic nerve and GFAP in the spinal cord. OA mice were also characterized by anxiety, depression, and neuroinflammation in the prefrontal cortex and hippocampus. In both stations, we found increased pro-inflammatory cytokines. In addition, PK upregulation and reactive astrogliosis in the hippocampus and microglia reactivity in the prefrontal cortex were detected. PC1 reduced joint inflammation and neuroinflammation in PNS and CNS and counteracted OA pain and emotional disturbances.

Mesenchymal stem cells alleviate dexamethasone-induced muscle atrophy in mice and the involvement of ERK1/2 signalling pathway

BACKGROUND

High dosage of dexamethasone (Dex) is an effective treatment for multiple diseases; however, it is often associated with severe side effects including muscle atrophy, resulting in higher risk of falls and poorer life quality of patients. Cell therapy with mesenchymal stem cells (MSCs) holds promise for regenerative medicine. In this study, we aimed to investigate the therapeutic efficacy of systemic administration of adipose-derived mesenchymal stem cells (ADSCs) in mitigating the loss of muscle mass and strength in mouse model of DEX-induced muscle atrophy.

METHODS

3-month-old female C57BL/6 mice were treated with Dex (20 mg/kg body weight, i.p.) for 10 days to induce muscle atrophy, then subjected to intravenous injection of a single dose of ADSCs ([Formula: see text] cells/kg body weight) or vehicle control. The mice were killed 7 days after ADSCs treatment. Body compositions were measured by animal DXA, gastrocnemius muscle was isolated for ex vivo muscle functional test, histological assessment and Western blot, while tibialis anterior muscles were isolated for RNA-sequencing and qPCR. For in vitro study, C2C12 myoblast cells were cultured under myogenic differentiation medium for 5 days following 100 [Formula: see text]M Dex treatment with or without ADSC-conditioned medium for another 4 days. Samples were collected for qPCR analysis and Western blot analysis. Myotube morphology was measured by myosin heavy chain immunofluorescence staining.

RESULTS

ADSC treatment significantly increased body lean mass (10-20%), muscle wet weight (15-30%) and cross-sectional area (CSA) (~ 33%) in DEX-induced muscle atrophy mice model and down-regulated muscle atrophy-associated genes expression (45-65%). Hindlimb grip strength (~ 37%) and forelimb ex vivo muscle contraction property were significantly improved (~ 57%) in the treatment group. Significant increase in type I fibres (~ 77%) was found after ADSC injection. RNA-sequencing results suggested that ERK1/2 signalling pathway might be playing important role underlying the beneficial effect of ADSC treatment, which was confirmed by ERK1/2 inhibitor both in vitro and in vivo.

CONCLUSIONS

ADSCs restore the pathogenesis of Dex-induced muscle atrophy with an increased number of type I fibres, stronger muscle strength, faster recovery rate and more anti-fatigue ability via ERK1/2 signalling pathway. The inhibition of muscle atrophy-associated genes by ADSCs offered this treatment as an intervention option for muscle-associated diseases. Taken together, our findings suggested that adipose-derived mesenchymal stem cell therapy could be a new treatment option for patient with Dex-induced muscle atrophy.

Characterization of prokineticin system in Crohn's disease pathophysiology and pain, and its modulation by alcohol abuse: A preclinical study

BACKGROUND

Crohn's disease-(CD) pathogenesis is still unknown and chronic pain is a frequent symptom in CD-patients. Identifying novel therapeutic targets and predisposing factors is a primary goal. In this regard, prokineticin system-(PKS) appears a promising target.

AIMS AND METHODS

TNBS-model was used. DAI, abdominal and visceral pain, and muscle strength were monitored. CD-mice were sacrificed at two times (day 7 and 14 after TNBS) in order to identify PKS involvement in CD pathophysiology and pain. PKS characterization was performed in mesenteric lymph nodes-(MLN), colon, myenteric plexus-(MP), dorsal root ganglia-(DRGs) and spinal cord-(SC). Inflammation/neuroinflammation was also assessed in the same tissues. In order to evaluate alcohol abuse as a possible trigger for CD and its effect on PKS activation, naïve mice were administered (oral-gavage) with ethanol for 10 consecutive days. PKS as well as inflammation/neuroinflammation were evaluated in MLN, colon and MP.

RESULTS

TNBS treated-mice showed a rapid increase in DAI, abdominal/visceral hypersensitivity and a progressive strength loss. In all tissue analysed of CD-mice, a quick and significant increase of mRNA of PKs and PKRs was observed, associated with an increase of pro-inflammatory cytokines (IL-1β, IL-6 and TNFα) and macrophage/glia markers (iba1, CD11b and GFAP) levels. In alcohol abuse model, ethanol induced in colon and MP a significant PKS activation accompanied by inflammation/neuroinflammation.

CONCLUSIONS

We can assume that PKS may be involved in CD development and pain. Furthermore, alcohol appears to activate PKS and may be a trigger factor for CD.

Serum starvation affects mitochondrial metabolism of adipose-derived stem/stromal cells

BACKGROUND AIMS

A large part of mesenchymal stromal cell (MSC) regenerative and immunomodulatory action is mediated by paracrine signaling. Hence, an increasing body of evidence acknowledges the potential of MSC secretome in a variety of preclinical and clinical scenarios. Mid-term serum deprivation is a common approach in the pipeline of MSC secretome production. Nevertheless, up to now, little is known about the impact of this procedure on the metabolic status of donor cells.

METHODS

Here, through untargeted differential metabolomics, we revealed an impairment of mitochondrial metabolism in adipose-derived MSCs exposed for 72 h to serum deprivation.

RESULTS

This evidence was further confirmed by the significant accumulation of reactive oxygen species and the reduction of succinate dehydrogenase activity. Probably as a repair mechanism, an upregulation of mitochondrial superoxide dismutase was also induced.

CONCLUSIONS

Of note, the analysis of mitochondrial functionality indicated that, despite a significant reduction of basal respiration and ATP production, serum-starved MSCs still responded to changes in energy demand. This metabolic phenotype correlates with the obtained evidence of mitochondrial elongation and branching upon starvation.

Conditioned Medium - Is it an Undervalued Lab Waste with the Potential for Osteoarthritis Management?

BACKGROUND

The approaches currently used in osteoarthritis (OA) are mainly short-term solutions with unsatisfactory outcomes. Cell-based therapies are still controversial (in terms of the sources of cells and the results) and require strict culture protocol, quality control, and may have side-effects. A distinct population of stromal cells has an interesting secretome composition that is underrated and commonly ends up as biological waste. Their unique properties could be used to improve the existing techniques due to protective and anti-ageing properties.

SCOPE OF REVIEW

In this review, we seek to outline the advantages of the use of conditioned media (CM) and exosomes, which render them superior to other cell-based methods, and to summarise current information on the composition of CM and their effect on chondrocytes.

MAJOR CONCLUSIONS

CM are obtainable from a variety of mesenchymal stromal cell (MSC) sources, such as adipose tissue, bone marrow and umbilical cord, which is significant to their composition. The components present in CMs include proteins, cytokines, growth factors, chemokines, lipids and ncRNA with a variety of functions. In most in vitro and in vivo studies CM from MSCs had a beneficial effect in enhance processes associated with chondrocyte OA pathomechanism.

GENERAL SIGNIFICANCE

This review summarises the information available in the literature on the function of components most commonly detected in MSC-conditioned media, as well as the effect of CM on OA chondrocytes in in vitro culture. It also highlights the need to standardise protocols for obtaining CM, and to conduct clinical trials to transfer the effects obtained in vitro to human subjects.

Pretreated Mesenchymal Stem Cells and Their Secretome: Enhanced Immunotherapeutic Strategies

Mesenchymal stem cells (MSCs) with self-renewing, multilineage differentiation and immunomodulatory properties, have been extensively studied in the field of regenerative medicine and proved to have significant therapeutic potential in many different pathological conditions. The role of MSCs mainly depends on their paracrine components, namely secretome. However, the components of MSC-derived secretome are not constant and are affected by the stimulation MSCs are exposed to. Therefore, the content and composition of secretome can be regulated by the pretreatment of MSCs. We summarize the effects of different pretreatments on MSCs and their secretome, focusing on their immunomodulatory properties, in order to provide new insights for the therapeutic application of MSCs and their secretome in inflammatory immune diseases.

Tissue-Protective and Anti-Inflammatory Landmark of PRP-Treated Mesenchymal Stromal Cells Secretome for Osteoarthritis

Bone-marrow-mesenchymal-stromal-cells (BMSCs)- and platelet-rich-plasma (PRP)-based therapies have shown potential for treating osteoarthritis (OA). Recently, the combination of these two approaches was proposed, with results that overcame those observed with the separate treatments, indicating a possible role of PRP in ameliorating BMSCs' regenerative properties. Since a molecular fingerprint of BMSCs cultivated in the presence of PRP is missing, the aim of this study was to characterize the secretome in terms of soluble factors and extracellular-vesicle (EV)-embedded miRNAs from the perspective of tissues, pathways, and molecules which frame OA pathology. One hundred and five soluble factors and one hundred eighty-four EV-miRNAs were identified in the PRP-treated BMSCs' secretome, respectively. Several soluble factors were related to the migration of OA-related immune cells, suggesting the capacity of BMSCs to attract lympho-, mono-, and granulocytes and modulate their inflammatory status. Accordingly, several EV-miRNAs had an immunomodulating role at both the single-factor and cell level, together with the ability to target OA-characterizing extracellular-matrix-degrading enzymes and cartilage destruction pathways. Overall, anti-inflammatory and protective signals far exceeded inflammation and destruction cues for cartilage, macrophages, and T cells. This study demonstrates that BMSCs cultivated in the presence of PRP release therapeutic molecules and give molecular ground for the use of this combined and innovative therapy for OA treatment.

Osteoarthritis Pain in Old Mice Aggravates Neuroinflammation and Frailty: The Positive Effect of Morphine Treatment

Knee osteoarthritis is a common cause of pain and disability in old subjects. Pain may predispose to the development of frailty. Studies on mechanisms underlying pain in osteoarthritis models during aging are lacking. In this work, we used the monosodium iodoacetate model of osteoarthritis in adult (11-week-old) and old (20-month-old) C57BL/6J mice to compare hypersensitivity, locomotion, neuroinflammation, and the effects of morphine treatment. After osteoarthritis induction in adult and old mice, weight-bearing asymmetry, mechanical allodynia, and thermal hyperalgesia similarly developed, while locomotion and frailty were more affected in old than in adult animals. When behavioral deficits were present, the animals were treated for 7 days with morphine. This opioid counteracts the behavioral alterations and the frailty index worsening both in adult and old mice. To address the mechanisms that underlie pain, we evaluated neuroinflammatory markers and proinflammatory cytokine expression in the sciatic nerve, DRGs, and spinal cord. Overexpression of cytokines and glia markers were present in osteoarthritis adult and old mice, but the activation was qualitatively and quantitatively more evident in aged mice. Morphine was able to counteract neuroinflammation in both age groups. We demonstrate that old mice are more vulnerable to pain's detrimental effects, but prompt treatment is successful at mitigating these effects.

Polythiophene-mediated light modulation of membrane potential and calcium signalling in human adipose-derived stem/stromal cells

Recent progress in the fields of regenerative medicine and tissue engineering has been strongly fostered both by the investigation of crucial cues, able to trigger the regeneration of damaged tissues, and by the development of ad hoc functional materials, capable of selectively (re-)activating relevant physiological pathways. In parallel to the successful realization of biochemical cues and the optimization of delivery protocols, the use of biophysical stimuli has been emerging as an alternative, highly effective strategy. Techniques based on electrical, magnetic and mechanical stimulation have been reported to efficiently direct differentiation of stem cells and modulate cell physiology at different developmental stages. In this framework, the use of optical stimulation represents a valuable approach, possibly overcoming current limitations of chemical cues, like limited spatial and temporal resolution and poor control over the extracellular environment. Surprisingly, the effects of light on the physiological properties (light toxicity, cell membrane potential, and cell ionic trafficking) of undifferentiated cells, as well as on their differentiation pathways, were investigated to a very limited extent and rarely quantified in a systematic way. In this work, we aim at clarifying the effects of optical excitation on the physiological behaviour of undifferentiated human adipose-derived stem cells (hASC), cultured on top of a light-sensitive conjugated polymer, region-regular poly-3-hexyl-thiophene (P3HT). Interestingly, we observe statistically significant modulation of the cell membrane potential, as well as noticeable effects on intracellular calcium signalling, triggered by P3HT excitation upon green light stimuli. Possible mechanisms involved in the signal transduction pathways are considered and critically discussed. The capability to modulate the physiological response of hASC upon photoexcitation, in a highly controlled and selective manner, provides a promptly available and non invasive diagnostic tool, thus contributing to the understanding of the complex machinery behind stem cells and material interfaces. Moreover, it may open the route to novel techniques to drive the differentiation path with unprecedented versatility and operational easiness.

Non-homologous use of adipose-derived cell and tissue therapies: Osteoarthritis as a case study

Adipose tissue is widely recognized as an abundant and accessible human tissue that serves as a source of cells and extracellular matrix scaffolds for regenerative surgical applications. Increasingly, orthopedic surgeons are turning to adipose tissue as a resource in their treatment of osteoarthritis and related conditions. In the U.S., the regulatory landscape governing the orthopedic surgical utilization of autologous and allogeneic adipose tissue remains complex. This manuscript reviews the Food and Drug Administration's nomenclature and guidance regarding adipose tissue products. Additionally, it surveys recent pre-clinical and clinical trial literature relating to the application of adipose-derived cells and tissues in the treatment of osteoarthritis.

Why Use Adipose-Derived Mesenchymal Stem Cells in Tendinopathic Patients: A Systematic Review

The aim of the present systematic review was to provide a clear overview of the clinical current research progress in the use of adipose-derived mesenchymal stem cells (ASCs) as an effective therapeutic option for the management of tendinopathies, pathologies clinically characterized by persistent mechanical pain and structural alteration of the tendons. The review was carried out using three databases (Scopus, ISI Web of Science and PubMed) and analyzed records from 2013 to 2021. Only English-language papers describing the isolation and manipulation of adipose tissue as source of ASCs and presenting ASCs as treatment for clinical tendinopathies were included. Overall, seven clinical studies met the inclusion criteria and met the minimum quality inclusion threshold. Data extraction and quality assessment were performed by groups of three reviewers. The available evidence showed the efficacy and safety of ASCs treatment for tendinopathies, although it lacked a clear description of the biomolecular mechanisms underlying the beneficial properties of ASCs.

Human neural stem cells secretome inhibits lipopolysaccharide-induced neuroinflammation through modulating microglia polarization by activating PPAR-γ

Neuroinflammation is one of the typical events in multiple neurodegenerative diseases, whereas microglia are the critical participants in the pathogenesis of neuroinflammation. Several studies suggest that neural stem cells (NSCs) present immunomodulatory benefits due to their paracrine products, which contain mounting trophic factors. In the current study, the anti-inflammatory effects of neural stem cells secretome (NSC-S) on lipopolysaccharide (LPS)-induced neuroinflammatory models were evaluated in vivo and the underlying mechanism was further investigated in vitro. It was revealed that NSC-S significantly attenuated the severity of LPS-induced behaviour disorders and inflammatory response in mice. In vitro studies found that NSC-S significantly promoted the polarization of microglia from proinflammatory M1 to anti-inflammatory M2 phenotype, and reduced the production of proinflammatory cytokines while elevated anti-inflammatory cytokines in BV2 cells. NSC-S promoted peroxisome proliferator-activated receptor gamma (PPAR-γ) pathway activation. However, these effects of NSC-S were abrogated by PPAR-γ inhibitor GW9662. Notably, the fatty acid binding protein 5 (FABP5) in NSC-S may mediate PPAR-γ activation and inflammation remission. In summary, NSC-S promotes the regression of LPS-induced microglia-mediated inflammation through the PPAR-γ pathway. This function might be achieved via FABP5.

Connection between Mesenchymal Stem Cells Therapy and Osteoclasts in Osteoarthritis

The use of mesenchymal stem cells constitutes a promising therapeutic approach, as it has shown beneficial effects in different pathologies. Numerous in vitro, pre-clinical, and, to a lesser extent, clinical trials have been published for osteoarthritis. Osteoarthritis is a type of arthritis that affects diarthritic joints in which the most common and studied effect is cartilage degradation. Nowadays, it is known that osteoarthritis is a disease with a very powerful inflammatory component that affects the subchondral bone and the rest of the tissues that make up the joint. This inflammatory component may induce the differentiation of osteoclasts, the bone-resorbing cells. Subchondral bone degradation has been suggested as a key process in the pathogenesis of osteoarthritis. However, very few published studies directly focus on the activity of mesenchymal stem cells on osteoclasts, contrary to what happens with other cell types of the joint, such as chondrocytes, synoviocytes, and osteoblasts. In this review, we try to gather the published bibliography in relation to the effects of mesenchymal stem cells on osteoclastogenesis. Although we find promising results, we point out the need for further studies that can support mesenchymal stem cells as a therapeutic tool for osteoclasts and their consequences on the osteoarthritic joint.

Towards Secretome Standardization: Identifying Key Ingredients of MSC-Derived Therapeutic Cocktail

The therapeutic potential of the conditioned medium (CM) derived from MSCs (mesenchymal stem/stromal cells) in disparate medical fields, from immunology to orthopedics, has been widely suggested by in vitro and in vivo evidences. Prior to MSC-CM use in clinical applications, appropriate quality controls are needed in order to assess its reproducibility. Here, we evaluated different CM characteristics, including general features and precise protein and lipid concentrations, in 3 representative samples from adipose-derived MSCs (ASCs). In details, we first investigated the size and distribution of the contained extracellular vesicles (EVs), lipid bilayer-delimited particles whose pivotal role in intercellular communication has been extensively demonstrated. Then, we acquired Raman signatures, providing an overlook of ASC-CM composition in terms of proteins, lipids, and nucleic acids. At last, we analyzed a panel of 200 molecules including chemokines, cytokines, receptors, and inflammatory and growth factors and searched for 32 lipids involved in cell signalling and inflammation. All ASC-CM contained a homogeneous and relevant number of EVs (1.0 × 10⁹ ± 1.1 × 10⁸ particles per million donor ASCs) with a mean size of 190 ± 5.2 nm, suggesting the appropriateness of the method for EV retaining and concentration. Furthermore, also Raman spectra confirmed a high homogeneity among samples, allowing the visualization of specific peaks for nucleic acids, proteins, and lipids. An in depth investigation that focused on 200 proteins involved in relevant biological pathways revealed the presence in all specimens of 104 factors. Of these, 26 analytes presented a high degree of uniformity, suggesting that the samples were particularly homogenous for a quarter of the quantified molecules. At last, lipidomic analysis allowed the quantification of 7 lipids and indicated prostaglandin-E2 and N-stearoylethanolamide as the most homogenous factors. In this study, we assessed that ASC-CM samples obtained with a standardized protocol present stable features spanning from Raman fingerprint to specific marker concentrations. In conclusion, we identified key ingredients that may be involved in ASC-CM therapeutic action and whose consistent levels may represent a promising quality control in the pipeline of its preparation for clinical applications.

Adipose-Derived Stem Cells Secretome and Its Potential Application in "Stem Cell-Free Therapy"

Adipose-derived stem cells (ASCs) secrete many cytokines, proteins, growth factors, and extracellular vesicles with beneficial outcomes that can be used in regenerative medicine. It has great potential, and the development of new treatment strategies using the ASCs secretome is of global interest. Besides cytokines, proteins, and growth factors, the therapeutic effect of secretome is hidden in non-coding RNAs such as miR-21, miR-24, and miR-26 carried via exosomes secreted by adequate cells. The whole secretome, including ASC-derived exosomes (ASC-exos) has been proven in many studies to have immunomodulatory, proangiogenic, neurotrophic, and epithelization activity and can potentially be used for neurodegenerative, cardiovascular, respiratory, inflammatory, and autoimmune diseases as well as wound healing treatment. Due to limitations in the use of stem cells in cell-based therapy, its secretome with emphasis on exosomes seems to be a reasonable and safer alternative with increased effectiveness and fewer side effects. Moreover, the great advantage of cell-free therapy is the possibility of biobanking the ASCs secretome. In this review, we focus on the current state of knowledge on the use of the ASCs secretome in stem cell-free therapy.