Cartilage responses to inflammatory stimuli and adipose stem/stromal cell-derived conditioned medium: Results from an ex vivo model.

Introduction: Osteoarthritis (OA), a chronic inflammatory joint disorder, still lacks effective therapeutic interventions. Consequently, the development of convenient experimental models is crucial. Recently, research has focused on the plasticity of Mesenchymal Stem/stromal Cells, particularly adipose-derived ones (ASCs), in halting OA progression. This study investigates the therapeutic potential of a cell-free approach, ASC-derived conditioned medium (CM), in reversing cytokine-induced OA markers in an ex vivo model of human cartilage explants. Methods: 4 mm cartilage punches, derived from the femoral heads of patients undergoing total hip replacement, were treated with 10 ng/ml TNFα, 1 ng/ml IL-1ß, or a combination of both, over a 3-day period. Analysis of OA-related markers, such as MMP activity, the release of NO and GAGs, and the expression of PTGS2, allowed for the selection of the most effective inflammatory stimulus. Subsequently, explants challenged with TNFα+IL-1ß were exposed to CM, consisting of a pool of concentrated supernatants from 72-h cultured ASCs, in order to evaluate its effect on cartilage catabolism and inflammation. Results: The 3-day treatment with both 10ng/ml TNFα and 1ng/ml IL-1ß significantly increased MMP activity and NO release, without affecting GAG release. The addition of CM significantly downregulated the abnormal MMP activity induced by the inflammatory stimuli, while also mildly reducing MMP3, MMP13, and PTGS2 gene expression. Finally, SOX9 and COL2A1 were downregulated by the cytokines, and further decreased by CM. Conclusion: The proposed cartilage explant model offers encouraging evidence of the therapeutic potential of ASC-derived CM against OA, and it could serve as a convenient ex vivo platform for drug screening.

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 1ß (IL-1ß) 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-ß1, 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.

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.

Significant association between FGFR1 mutation frequency and age in central giant cell granuloma.

Central giant cell granulomas (CGCG) are rare intraosseous osteolytic lesions of uncertain aetiology. Despite the benign nature of this neoplasia, the lesions can rapidly grow and become large, painful, invasive, and destructive. The identification of molecular drivers could help in the selection of targeted therapies for specific cases. TRPV4, KRAS and FGFR1 mutations have been associated with these lesions but no correlation between the mutations and patient features was observed so far. In this study, we analysed 17 CGCG cases of an Italian cohort and identified an interesting and significant (p=0.0021) correlation between FGFR1 mutations and age. In detail, FGFR1 mutations were observed frequently and exclusively in CGCG from young (<18 years old) patients (4/5 lesions, 80%). Furthermore, the combination between ours and previously published data confirmed a significant difference in the frequency of FGFR1 mutations in CGCG from patients younger than 18 years at the time of diagnosis (9/23 lesions, 39%) when compared to older patients (1/31 lesions, 0.03%; p=0.0011), thus corroborating our observation in a cohort of 54 patients. FGFR1 variants in young CGCG patients could favour fast lesion growth, implying that they seek medical attention earlier. Our observation might help prioritise candidates for FGFR1 testing, thus opening treatment options with FGFR inhibitors.

Human Osteochondral Explants as an Ex Vivo Model of Osteoarthritis for the Assessment of a Novel Class of Orthobiologics.

Osteoarthritis (OA) is a highly prevalent joint disease still lacking effective treatments. Its multifactorial etiology hampers the development of relevant preclinical models to evaluate innovative therapeutic solutions. In the last decade, the potential of Mesenchymal Stem Cell (MSC) secretome, or conditioned medium (CM), has emerged as an alternative to cell therapy. Here, we investigated the effects of the CM from adipose MSCs (ASCs), accounting for both soluble factors and extracellular vesicles, on human osteochondral explants. Biopsies, isolated from total knee replacement surgery, were cultured without additional treatment or with the CM from 106 ASCs, both in the absence and in the presence of 10 ng/mL TNFα. Tissue viability and several OA-related hallmarks were monitored at 1, 3 and 6 days. Specimen viability was maintained over culture. After 3 days, TNFα induced the enhancement of matrix metalloproteinase activity and glycosaminoglycan release, both efficiently counteracted by CM. The screening of inflammatory lipids, proteases and cytokines outlined interesting modulations, driving the attention to new players in the OA process. Here, we confirmed the promising beneficial action of ASC secretome in the OA context and profiled several bioactive factors involved in its progression, in the perspective of accelerating an answer to its unmet clinical needs.

Dynamics of Connexin 43 Down Modulation in Human Articular Chondrocytes Stimulated by Tumor Necrosis Factor Alpha.

Connexin 43 (Cx43) exerts pivotal functions in articular chondrocytes (CH). It is involved in the communication among cells and between cells and the extracellular environment, and it contributes to the maintenance of the correct cell phenotype. The pro-inflammatory cytokine TNFα induces a reduction in Cx43 expression in CH. Here, we studied the dynamics of this decrease in expression. We evaluated Cx43 protein and gene expression and the involvement of C-terminal domain (CTD) cleavage and proteasomal degradation. Treatments able to counteract TNFα action were also examined, together with Gap Junction (GJ) functionality and Cx43 localization. TNFα induced a significant reduction in Cx43 expression already at day 1, and the down modulation reached a peak at day 3 (-46%). The decrease was linked to neither gene expression modulation nor CTD cleavage. Differently, the proteasome inhibitor MG132 reverted TNFα effect, indicating the involvement of proteasomal degradation in Cx43 reduction. In addition, the co-treatment with the anabolic factor TGF-ß1 restored Cx43 levels. Cx43 decrease occurred both at the membrane level, where it partially influenced GJ communication, and in the nucleus. In conclusion, TNFα induced a rapid and lasting reduction in Cx43 expression mostly via the proteasome. The down modulation could be reverted by cartilage-protective factors such as MG132 and TGF-ß1. These findings suggest a possible involvement of Cx43 perturbation during joint inflammation.

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.

Raman Fingerprint of Extracellular Vesicles and Conditioned Media for the Reproducibility Assessment of Cell-Free Therapeutics.

Extracellular Vesicles (EVs) and Conditioned Medium (CM) are promising cell-free approaches to repair damaged and diseased tissues for regenerative rehabilitation purposes. They both entail several advantages, mostly in terms of safety and handling, compared to the cell-based treatment. Despite the growing interest in both EVs and CM preparations, in the light of a clinical translation, a number of aspects still need to be addressed mainly because of limits in the reproducibility and reliability of the proposed protocols. Raman spectroscopy (RS) is a non-destructive vibrational investigation method that provides detailed information about the biochemical composition of a sample, with reported ability in bulk characterization of clusters of EVs from different cell types. In the present brief report, we acquired and compared the Raman spectra of the two most promising cell-free therapeutics, i.e., EVs and CM, derived from two cytotypes with a history in the field of regenerative medicine, adipose-derived mesenchymal stem/stromal cells (ASCs) and dermal fibroblasts (DFs). Our results show how RS can verify the reproducibility not only of EV isolation, but also of the whole CM, thus accounting for both the soluble and the vesicular components of cell secretion. RS can provide hints for the identification of the soluble factors that synergistically cooperate with EVs in the regenerative effect of CM. Still, we believe that the application of RS in the pipeline of cell-free products preparation for therapeutic purposes could help in accelerating translation to clinics and regulatory approval.

Proteomic analysis of extracellular vesicles and conditioned medium from human adipose-derived stem/stromal cells and dermal fibroblasts.

Conditioned medium (CM) and extracellular vesicles (EV) from Adipose-derived Stem/stromal cells (ASC) and Dermal fibroblasts (DF) represent promising tools for therapeutic applications. Which one should be preferred is still under debate and no direct comparison of their proteome has been reported yet. Here, we apply quantitative proteomics to explore the protein composition of CM and EV from the two cell types. Data are available via ProteomeXchange (identifier PXD020219). We identified 1977 proteins by LC-MS/MS proteomic analysis. Unsupervised clustering analysis and PCA recognized CM and EV as separate groups. We identified 68 and 201 CM and EV specific factors. CM were enriched in proteins of endoplasmic reticulum, Golgi apparatus and lysosomes, whereas EV contained a large amount of GTPases, ribosome and translation factors. The analysis of ASC and DF secretomes revealed the presence of cell type-specific proteins. ASC-CM and -EV carried factors involved in ECM organization and immunological regulation, respectively. Conversely, DF-CM and -EV were enriched in epithelium development associated factors and -EV in Wnt signaling factors. In conclusion, this analysis provides evidence of a different protein composition between CM and EV and of the presence of cell type-specific bioactive mediators suggesting their specific future use as advanced therapy medicinal products. SIGNIFICANCE: The use of cell secretome presents several advantages over cell therapy such as the lower risks associated to the administration step and the avoidance of any potential risk of malignant transformation. The main secretome preparations consist in concentrated conditioned medium (CM) and extracellular vesicles (EV). Both of them showed well-documented therapeutic potentials. However, it is still not clear in which case it should be better to use one preparation over the other and an exhaustive comparison between their proteome has not been performed yet. The choice of the cell source is another relevant aspect that still needs to be addressed. In order to shed light on these questions we explored the protein composition of CM and EV obtained from Adipose-derived Stem/stromal Cells (ASC) and Dermal Fibroblasts (DF), by a comprehensive quantitative proteomics approach. The analysis showed a clear distinction between CM and EV proteome. CM were enriched in proteins of endoplasmic reticulum, Golgi apparatus and lysosomes, whereas EV contained a large amount of GTPases, ribosome and translation-related factors. Furthermore, the analysis of ASC and DF secretomes revealed specific biological processes for the different cell products. ASC secretome presented factors involved in ECM organization (hyaluronan and glycosaminoglycan metabolism) and immunological regulation (e.g. macrophage and IkB/NFkB signaling regulation), respectively. On the other hand, DF-CM and -EV were both enriched in epithelium development associated factors, whilst DF-CM in proteins involved in cellular processes regulation and -EV in Wnt signaling factors. In conclusion, our study shed a light on the different protein composition of CM and EV of two promising cell types, spanning from basic processes involved in secretion to specific pathways supporting their therapeutic potential and their possible future use as advanced therapy medicinal products.

Comparison of two ASC-derived therapeutics in an in vitro OA model: secretome versus extracellular vesicles.

BACKGROUND: In the last years, several clinical trials have proved the safety and efficacy of adipose-derived stem/stromal cells (ASC) in contrasting osteoarthritis (OA). Since ASC act mainly through paracrine mechanisms, their secretome (conditioned medium, CM) represents a promising therapeutic alternative. ASC-CM is a complex cocktail of proteins, nucleic acids, and lipids released as soluble factors and/or conveyed into extracellular vesicles (EV). Here, we investigate its therapeutic potential in an in vitro model of OA. METHODS: Human articular chondrocytes (CH) were induced towards an OA phenotype by 10 ng/ml TNFα in the presence of either ASC-CM or EV, both deriving from 5 × 105 cells, to evaluate the effect on hypertrophic, catabolic, and inflammatory markers. RESULTS: Given the same number of donor cells, our data reveal a higher therapeutic potential of ASC-CM compared to EV alone that was confirmed by its enrichment in chondroprotective factors among which TIMP-1 and -2 stand out. In details, only ASC-CM significantly decreased MMP activity (22% and 29% after 3 and 6 days) and PGE2 expression (up to 40% at day 6) boosted by the inflammatory cytokine. Conversely, both treatments down-modulated of ~ 30% the hypertrophic marker COL10A1. CONCLUSIONS: These biological and molecular evidences of ASC-CM beneficial action on CH with an induced OA phenotype may lay the basis for its future clinical translation as a cell-free therapeutic in the management of OA.

Management of Osteoarthritis During the COVID-19 Pandemic.

The pandemic spread of the new coronavirus disease 2019 (COVID-19) infection in China first, and all over the world at present, has become a global health emergency due to the rapidly increasing number of affected patients. Currently, a clear relationship between COVID-19 infection incidence and/or complications due to chronic or occasional treatments for other pathologies is still not clear, albeit the COVID-19 pandemic may condition the treatment strategy of complex disorders, such as osteoarthritis (OA). Importantly, OA is the most common age-related joint disease, affecting more than 80% of people older than the age of 55, an age burden also shared with the highest severity in COVID-19 patients. OA patients often show a large array of concomitant pathologies, such as diabetes, inflammation, and cardiovascular diseases that are again shared with COVID-19 patients and may therefore increase complications. Moreover, different OA treatments, such as NSAIDs, paracetamol, corticosteroids, opioids, or other molecules have a wide array of iatrogenic effects, potentially increasing COVID-19 secondary infection incidence or complications. In this review we critically analyze the evidence on either negative or positive effects of drugs commonly used to manage OA in this particular scenario. This would provide orthopedic surgeons in particular, and physicians, pharmacologists, and clinicians in general, a comprehensive description about the safety of the current pharmacological approaches and a decision-making tool to treat their OA patients as the coronavirus pandemic continues.

Adipose-derived stromal cell secretome reduces TNFα-induced hypertrophy and catabolic markers in primary human articular chondrocytes.

Recent clinical trials show the efficacy of Adipose-derived Stromal Cells (ASCs) in contrasting the osteoarthritis scenario. Since it is quite accepted that ASCs act predominantly through a paracrine mechanism, their secretome may represent a valid therapeutic substitute. The aim of this study was to investigate the effects of ASC conditioned medium (ASC-CM) on TNFα-stimulated human primary articular chondrocytes (CHs). CHs were treated with 10 ng/ml TNFα and/or ASC-CM (1:5 recipient:donor cell ratio). ASC-CM treatment blunted TNFα-induced hypertrophy, reducing the levels of Osteocalcin (-37%), Collagen X (-18%) and MMP-13 activity (-61%). In addition, it decreased MMP-3 activity by 59%. We showed that the reduction of MMP activity correlates to the abundance of TIMPs (Tissue Inhibitors of MMPs) in ASC secretome (with TIMP-1 exceeding 200 ng/ml and TIMP-2/3 in the ng/ml range) rather than to a direct down-modulation of the expression and/or release of these proteases. In addition, ASC secretome contains high levels of other cartilage protecting factors, i.e. OPG and DKK-1. ASC-CM comprises cartilage-protecting factors and exerts anti-hypertrophic and anti-catabolic effects on TNFα-stimulated CHs in vitro. Our results support a future use of this cell-derived but cell-free product as a therapeutic approach in the management of osteoarthritis.

Microfragmented human fat tissue is a natural scaffold for drug delivery: Potential application in cancer chemotherapy.

Localization of chemotherapy at the tumor site can improve therapeutic efficacy and reduce systemic toxicity. In previous studies we have shown that mesenchymal stromal cells (MSCs) isolated from bone marrow or adipose tissue can be loaded with the anti-cancer drug Paclitaxel (PTX) and kill cancer cells when localized nearby. We here investigated the capacity of human micro-fragmented adipose tissue (MFAT), used as a natural scaffold of MSCs, to deliver PTX with the idea to improve local drug concentration and to prolong the therapeutic activity. Surprisingly, we found that both fresh but also devitalized MFAT (DMFAT) (by freezing/thawing procedure) were able to deliver and release significant amount of PTX, killing several human cancer cell lines in vitro with a long lasting activity. In an orthotopic mice model of Neuroblastoma (NB) transplant, DMFAT loaded with PTX prevents or delays NB relapse when placed in the surgical area of tumor resection, without any collateral toxicity. We concluded that MFAT, but also DMFAT, may represent very innovative natural biomaterials able to localize and release anti-cancer molecules at the tumor site, helping to fight cancer in human.

Raman spectroscopy as a quick tool to assess purity of extracellular vesicle preparations and predict their functionality.

Extracellular vesicles (EVs) from a variety of stem cell sources are believed to harbour regenerative capacity, which may be exploited for therapeutic purposes. Because of EV interaction with other soluble secreted factors, EV activity may depend on the employed purification method, which limits cross-study comparisons and therapeutic development. Raman spectroscopy (RS) is a quick and easy method to assess EV purity and composition, giving in-depth biochemical overview on EV preparation. Hereby, we show how this method can be used to characterise EVs isolated from human liver stem cells and bone marrow mesenchymal stem/stromal cells by means of conventional ultracentrifugation (UC) and size exclusion chromatography (SEC) protocols. The obtained EV preparations were demonstrated to be characterised by different degrees of purity and a specific Raman fingerprint that represents both the cell source and the isolation procedure used. Moreover, RS provided useful hints to explore the factors underlying the functional diversity of EV preparations from the same cell source, thus representing a valuable tool to assess EV quality prior to functional assays or therapeutic application.

In Vitro Anticancer Activity of Extracellular Vesicles (EVs) Secreted by Gingival Mesenchymal Stromal Cells Primed with Paclitaxel.

Interdental papilla are an interesting source of mesenchymal stromal cells (GinPaMSCs), which are easy to isolate and expand in vitro. In our laboratory, GinPaMSCs were isolated, expanded, and characterized by studying their secretome before and after priming with paclitaxel (PTX). The secretome of GinPaMSCs did not affect the growth of cancer cell lines tested in vitro, whereas the secretome of GinPaMSCs primed with paclitaxel (GinPaMSCs/PTX) exerted a significant anticancer effect. GinPaMSCs were able to uptake and then release paclitaxel in amounts pharmacologically effective against cancer cells, as demonstrated in vitro by the direct activity of GinPaMSCs/PTX and their secretome against both human pancreatic carcinoma and squamous carcinoma cells. PTX was associated with extracellular vesicles (EVs) secreted by cells (EVs/PTX), suggesting that PTX is incorporated into exosomes during their biogenesis. The isolation of mesenchymal stromal cells (MSCs) from gingiva is less invasive than that from other tissues (such as bone marrow and fat), and GinPaMSCs provide an optimal substrate for drug-priming to obtain EVs/PTX having anticancer activity. This research may contribute to develop new strategies of cell-mediated drug delivery by EVs that are easy to store without losing function, and could have a superior safety profile in therapy.

Nitrogen Containing Bisphosphonates Impair the Release of Bone Homeostasis Mediators and Matrix Production by Human Primary Pre-Osteoblasts.

Bisphosphonates (BPs) represent the first-line treatment for a wide array of bone disorders. Despite their well-known action on osteoclasts, the effects they induce on osteoblasts are still unclear. In order to shed light on this aspect we evaluated the impact of two nitrogen containing bisphosphonates, Alendronate (ALN) and Zoledronate (ZOL), on human primary pre-osteoblasts. At first, we showed an inhibitory effect on cell viability and alkaline phosphatase activity starting from µM concentrations of both drugs. In addition, an inhibitory trend on mineralized nodules deposition was observed. Then low doses of both ALN and ZOL rapidly increased the release of the pro-inflammatory mediators TNFα and IL-1ß, while increased DKK-1 and Sclerostin, both inhibitors of osteoblastogenesis. Finally, ALN and 10-7M ZOL decreased the expression of type I Collagen and Osteopontin, while both drugs slightly stimulated SPARC production. With these results, we would like to suggest a direct inhibitory action on bone-forming cells by nitrogen containing bisphosphonates.

Uptake-release by MSCs of a cationic platinum(II) complex active in vitro on human malignant cancer cell lines.

In this study, the in vitro stability of cisplatin (CisPt) and cationic platinum(II)-complex (caPt(II)-complex) and their in vitro activity (antiproliferative and anti-angiogenic properties) were investigated against three aggressive human tumor cell lines. caPt(II)-complex shown a high stability until 9 days of treatment and displayed a significant and higher activity than CisPt against both NCI-H28 mesothelioma (19.37 ± 9.57 µM versus 34.66 ± 7.65 µM for CisPt) and U87 MG glioblastoma (19.85 ± 0.97 µM versus 54.14 ± 3.19 for CisPt). Mesenchymal Stromal Cells (AT-MSCs) showed a significant different sensitivity (IC50 = 71.9 ± 15.1 µM for caPt(II)-complex and 8.7 ± 4.5 µM for CisPt) to the antiproliferative activity of caPt(II)-complex and CisPt. The ability of MSCs to uptake both the drugs in a similar amount of 2.49 pM /cell, suggested a possible development of new therapies based on cell mediated drug delivery.

Differential Proteomic Analysis Predicts Appropriate Applications for the Secretome of Adipose-Derived Mesenchymal Stem/Stromal Cells and Dermal Fibroblasts.

The adult stem cell secretome is currently under investigation as an alternative to cell-based therapy in regenerative medicine, thanks to the remarkable translational opportunity and the advantages in terms of handling and safety. In this perspective, we recently demonstrated the efficient performance of the adipose-derived mesenchymal stem/stromal cell (ASC) secretome in contrasting neuroinflammation in a murine model of diabetic neuropathy, where the administration of factors released by dermal fibroblasts (DFs) did not exert any effect. Up to now, the complex mixture of the constituents of the conditioned medium from ASCs has not been fully deepened, although its appropriate characterization is required in the perspective of a clinical use. Herein, we propose the differential proteomic approach for the identification of the players accounting for the functional effects of the cell secretome with the aim to unravel its appropriate applications. Out of 967 quantified proteins, 34 and 62 factors were found preponderantly or exclusively secreted by ASCs and DFs, respectively. This approach led to the recognition of distinct functions related to the conditioned medium of ASCs and DFs, with the former being involved in the regulation of neuronal death and apoptosis and the latter in bone metabolism and ossification. The proosteogenic effect of DF secretome was validated in vitro on human primary osteoblasts, providing a proof of concept of its osteoinductive potential. Besides discovering new applications of the cell type-specific secretome, the proposed strategy could allow the recognition of the cocktail of bioactive factors which might be responsible for the effects of conditioned media, thus providing a solid rationale to the implementation of a cell-free approach in several clinical scenarios involving tissue regeneration.

Impact of Dental Implant Surface Modifications on Adhesion and Proliferation of Primary Human Gingival Keratinocytes and Progenitor Cells.

The success of dental implants depends mainly on osseointegration and gingival sealing. Therefore, early attachment and spreading of epithelial cells might be critical for a positive outcome. Research in dental implant materials has primarily focused on surface roughness, defined by the average roughness (Ra) index, as it promotes the process of osseointegration. This study explored its influence on soft tissue attachment by looking mainly at adhesion, proliferation, and spreading of primary human cells belonging to the epithelial lineage. Characterized human gingival keratinocytes, gingival and epithelial progenitor cells were seeded on machined (S1; Ra = 0.3 to 0.6 µm), Ti-Unite (S2; Ra = 1.2 µm), and SLA (S3; Ra = 2 µm) implants. Cell adhesion with early proliferation and spreading were evaluated by combining a biochemical vitality test with imaging analyses. Findings showed that adhesion was significantly higher on S1 (36% ± 2%) and S2 (44% ± 7%) than on S3 (23% ± 6%), while early proliferation was slightly improved on S1. The resulting data, obtained through an innovative and easily reproducible in vitro method, suggest that implant surface roughness affects epithelial cell adhesion and proliferation.

Drug Loaded Gingival Mesenchymal Stromal Cells (GinPa-MSCs) Inhibit In Vitro Proliferation of Oral Squamous Cell Carcinoma.

Human mesenchymal stromal cells (MSCs) have been widely investigated both for regenerative medicine and their antinflammatory/immunomodulatory capacity. However, their ability to home pathological tissues suggested the development of strategies for using MSCs as carrier to deliver drug into tumor microenvironment. MSCs obtained from different tissues can be loaded in vitro with anti-cancer drugs by a simple procedures. In this report, we studied MSCs isolated and expanded from gingival papilla (GinPa-MSCs), by testing their ability to uptake and release three important anti-neoplastic drugs: Paclitaxel (PTX), Doxorubicin (DXR) and Gemcitabine (GCB). The efficacy of drugs releasing GinPa-MSCs was studied on a pancreatic cancer cell line and confirmed in vitro against a line of tongue squamous cell carcinoma (SCC154). Our results demonstrated that GinPa-MSCs efficiently incorporate the drugs and then released them in active form and in sufficient amount to produce a dramatic inhibition of squamous cell carcinoma growth in vitro. If compared with other MSCs sources, the collection of GinPa-MSCs is poorly invasive and cells can be easily expanded and efficiently loaded with anti cancer drugs. In particular, gemcitabine loaded GinPa-MSCs provide a good "cell-mediated drug delivery system" for a future potential application in the context of the oral oncology.