Saliva and Saliva Extracellular Vesicles for Biomarker Candidate Identification-Assay Development and Pilot Study in Amyotrophic Lateral Sclerosis.

Saliva is gaining increasing attention as a source of biomarkers due to non-invasive and undemanding collection access. Extracellular vesicles (EVs) are nano-sized, cell-released particles that contain molecular information about their parent cells. In this study, we developed methods for saliva biomarker candidate identification using EV-isolation and proteomic evaluation. We used pooled saliva samples for assay development. EVs were isolated using membrane affinity-based methods followed by their characterization using nanoparticle tracking analysis and transmission electron microscopy. Subsequently, both saliva and saliva-EVs were successfully analyzed using proximity extension assay and label-free quantitative proteomics. Saliva-EVs had a higher purity than plasma-EVs, based on the expression of EV-proteins and albumin. The developed methods could be used for the analysis of individual saliva samples from amyotrophic lateral sclerosis (ALS) patients and controls (n = 10 each). The starting volume ranged from 2.1 to 4.9 mL and the amount of total isolated EV-proteins ranged from 5.1 to 42.6 µg. Although no proteins were significantly differentially expressed between the two groups, there was a trend for a downregulation of ZNF428 in ALS-saliva-EVs and an upregulation of IGLL1 in ALS saliva. In conclusion, we have developed a robust workflow for saliva and saliva-EV analysis and demonstrated its technical feasibility for biomarker discovery.

A pilot study using proximity extension assay of cerebrospinal fluid and its extracellular vesicles identifies novel amyotrophic lateral sclerosis biomarker candidates.

Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disorder which is characterized by progressive degeneration of the motor system. Typically, the disease starts with focal weakness which spreads to involve most muscles and leads to death from respiratory failure within five years of diagnosis. Due to the heterogenic nature of the disease, diagnostics is complex, and it generally takes twelve months from symptom-onset to diagnosis. The discovery of novel biomarkers could lead to accelerated diagnosis, earlier start of treatment, improved patient-segmentation, and treatment follow-up as well as an increased insight into the pathology. Here, we analyzed cerebrospinal fluid (CSF) and CSF-derived extracellular vesicles (CSF-EVs) from ALS-patients and matched controls (n = 9 each) using the ultra-sensitive proximity extension assay (PEA), cardiovascular III-panel. On average, 84 and 61 proteins could be detected in CSF and CSF-EVs respectively. In CSF, three proteins were significantly upregulated in ALS-patients (Junctional Adhesion Molecule A Protein, Tumor necrosis factor receptor 2 and Chitinase 1) while myoglobin was down-regulated. In CSF-EVs, no significantly differentially expressed proteins were identified, but there was a trend for downregulation of Perlecan. To our knowledge, only CHIT1 has been previously described as a CSF-based biomarker candidate for ALS. By combining the four differentially expressed markers in CSF and support vector machine algorithm, all ALS patients and 8 of 9 controls were correctly classified. In conclusion, we here demonstrate the feasibility of using PEA of CSF and CSF-EVs for biomarker discovery and propose three de novo biomarker candidates for ALS, however, further studies are necessary to demonstrate clinical usability.

Extracellular Vesicle Therapeutics in Regenerative Medicine.

Extracellular vesicles (EVs) are nano-sized, cell-released vesicles which contain lipids, proteins, and nucleic acids derived from the parental cells. EVs play an important role in intercellular communication and influence both physiological and pathological conditions. They are increasingly explored as potential therapeutic agents since they can cross biological barriers, their cargo is protected from degradation and they are involved in the transfer of bioactive components. EVs can promote tissue regeneration and might be alternatives to cell therapy. They can be used both in their native form, and as delivery vehicles for therapeutic agents. However, there are many hurdles to overcome for broad clinical application of EVs as therapeutics. Here, we review recent conditions regarding EVs therapeutics in regenerative medicine.

Correction to: RNA-sequencing reveals positional memory of multipotent mesenchymal stromal cells from oral and maxillofacial tissue transcriptomes.

An amendment to this paper has been published and can be accessed via the original article.

RNA-sequencing reveals positional memory of multipotent mesenchymal stromal cells from oral and maxillofacial tissue transcriptomes.

BACKGROUND: Multipotent mesenchymal stromal cells (MSCs) can be isolated from numerous tissues and are attractive candidates for therapeutic clinical applications due to their immunomodulatory and pro-regenerative capacity. Although the minimum criteria for defining MSCs have been defined, their characteristics are known to vary depending on their tissue of origin. RESULTS: We isolated and characterized human MSCs from three different bones (ilium (I-MSCs), maxilla (Mx-MSCs) and mandible (Md-MSCs)) and proceeded with next generation RNA-sequencing. Furthermore, to investigate the gene expression profiles among other cell types, we obtained RNA-seq data of human embryonic stem cells (ESCs) and several types of MSCs (periodontal ligament-derived MSCs, bone marrow-derived MSCs, and ESCs-derived MSCs) from the Sequence Reads Archive and analyzed the transcriptome profile. We found that MSCs derived from tissues of the maxillofacial region, such as the jaw bone and periodontal ligament, were HOX-negative, while those derived from other tissues were HOX-positive. We also identified that MSX1, LHX8, and BARX1, an essential regulator of craniofacial development, were strongly expressed in maxillofacial tissue-derived MSCs. Although MSCs may be divided into two distinct groups, the cells originated from over the neck or not, on the basis of differences in gene expression profile, the expression patterns of all CD antigen genes were similar among different type of MSCs, except for ESCs. CONCLUSIONS: Our findings suggest that MSCs from different anatomical locations, despite meeting general characterization criteria, have remarkable differences in gene expression and positional memory. Although stromal cells from different anatomical sources are generally categorized as MSCs, their differentiation potential and biological functions vary. We suggested that MSCs may retain an original tissue memory about the developmental process, including gene expression profiles. This could have an important impact when choosing an appropriate cell source for regenerative therapy using MSCs.

Analysis of Cerebrospinal Fluid Extracellular Vesicles by Proximity Extension Assay: A Comparative Study of Four Isolation Kits.

There is a lack of reliable biomarkers for disorders of the central nervous system (CNS), and diagnostics still heavily rely on symptoms that are both subjective and difficult to quantify. The cerebrospinal fluid (CSF) is a promising source of biomarkers due to its close connection to the CNS. Extracellular vesicles are actively secreted by cells, and proteomic analysis of CSF extracellular vesicles (EVs) and their molecular composition likely reflects changes in the CNS to a higher extent compared with total CSF, especially in the case of neuroinflammation, which could increase blood-brain barrier permeability and cause an influx of plasma proteins into the CSF. We used proximity extension assay for proteomic analysis due to its high sensitivity. We believe that this methodology could be useful for de novo biomarker discovery for several CNS diseases. We compared four commercially available kits for EV isolation: MagCapture and ExoIntact (based on magnetic beads), EVSecond L70 (size-exclusion chromatography), and exoEasy (membrane affinity). The isolated EVs were characterized by nanoparticle tracking analysis, ELISA (CD63, CD81 and albumin), and proximity extension assay (PEA) using two different panels, each consisting of 92 markers. The exoEasy samples did not pass the built-in quality controls and were excluded from downstream analysis. The number of detectable proteins in the ExoIntact samples was considerably higher (~150% for the cardiovascular III panel and ~320% for the cell regulation panel) compared with other groups. ExoIntact also showed the highest intersample correlation with an average Pearson's correlation coefficient of 0.991 compared with 0.985 and 0.927 for MagCapture and EVSecond, respectively. The median coefficient of variation was 5%, 8%, and 22% for ExoIntact, MagCapture, and EVSecond, respectively. Comparing total CSF and ExoIntact samples revealed 70 differentially expressed proteins in the cardiovascular III panel and 17 in the cell regulation panel. To our knowledge, this is the first time that CSF EVs were analyzed by PEA. In conclusion, analysis of CSF EVs by PEA is feasible, and different isolation kits give distinct results, with ExoIntact showing the highest number of identified proteins with the lowest variability.

Oral keratinocyte-derived exosomes regulate proliferation of fibroblasts and epithelial cells.

Extracellular vesicles (EVs), including exosomes, are small membrane-bound particles released by cells. From a therapeutic point of view, EVs can often convey similar biological function as their parent cell. Grafts originating from oral mucosa have frequently been used in regenerative medicine, and we have previously described the use of oral cell sheets to prevent stricture formation of the esophagus. Further, we recently found that exosomes derived from these cell sheets have pro-regenerative effect on skin wound healing. Here, we have isolated exosomes from conditioned media from oral keratinocyte ("OKEx") and dermal fibroblast ("FEx") cultures. The exosomes were probed for classical EV-markers by western blot (CD9, annexin V and Flotillin-1), FEx were positive for all markers while OKEx were positive only for CD9. Tunable resistive pulse sensing indicated a mean size of around 110 nm and transmission electron microscopy showed a spherical morphology, for both groups. After fluorescent labelling, we studied the uptake of exosomes co-cultured with fibroblasts or keratinocytes. Signal from OKEx could be detected after 90 min, and signal could be detected in all groups after 16 h. Finally we studied the exosomes' modulation of cell proliferation. Both groups suppressed proliferation of healthy keratinocyte and fibroblasts, at some doses to similar levels as dexamethasone (a drug commonly used to prevent stricture formation). In contrast, the exosomes also suppressed the proliferation of the carcinoma cell line TR146, while dexamethasone had no effect. In conclusion, we believe that exosome-signaling might be one of the mode-of-actions of cell sheet-therapy for stricture prevention.

Autologous Peripheral Blood Mononuclear Cells as Treatment in Refractory Acute Respiratory Distress Syndrome.

BACKGROUND: Acute respiratory distress syndrome (ARDS) is a devastating disorder. Despite enormous efforts in clinical research, effective treatment options are lacking, and mortality rates remain unacceptably high. OBJECTIVES: A male patient with severe ARDS showed no clinical improvement with conventional therapies. Hence, an emergent experimental intervention was performed. METHODS: We performed intratracheal administration of autologous peripheral blood-derived mononuclear cells (PBMCs) and erythropoietin (EPO). RESULTS: We found that after 2 days of initial PBMC/EPO application, lung function improved and extracorporeal membrane oxygenation (ECMO) support was reduced. Bronchoscopy and serum inflammatory markers revealed reduced inflammation. Additionally, serum concentration of miR-449a, b, c and miR-34a, a transient upregulation of E-cadherin and associated chromatin marks in PBMCs indicated airway epithelial differentiation. Extracellular vesicles from PBMCs demonstrated anti-inflammatory capacity in a TNF-α-mediated nuclear factor-x03BA;B in vitro assay. Despite improving respiratory function, the patient died of multisystem organ failure on day 38 of ECMO treatment. CONCLUSIONS: This case report provides initial encouraging evidence to use locally instilled PBMC/EPO for treatment of severe refractory ARDS. The observed clinical improvement may partially be due to the anti-inflammatory effects of PBMC/EPO to promote tissue regeneration. Further studies are needed for more in-depth understanding of the underlying mechanisms of in vivo regeneration.

Modelling biological cell attachment and growth on adherent surfaces.

A mathematical model, in the form of an integro-partial differential equation, is presented to describe the dynamics of cells being deposited, attaching and growing in the form of a monolayer across an adherent surface. The model takes into account that the cells suspended in the media used for the seeding have a distribution of sizes, and that the attachment of cells restricts further deposition by fragmenting the parts of the domain unoccupied by cells. Once attached the cells are assumed to be able to grow and proliferate over the domain by a process of infilling of the interstitial gaps; it is shown that without cell proliferation there is a slow build up of the monolayer but if the surface is conducive to cell spreading and proliferation then complete coverage of the domain by the monolayer can be achieved more rapidly. Analytical solutions of the model equations are obtained for special cases, and numerical solutions are presented for parameter values derived from experiments of rat mesenchymal stromal cells seeded onto thin layers of collagen-coated polyethylene terephthalate electrospun fibers. The model represents a new approach to describing the deposition, attachment and growth of cells over adherent surfaces, and should prove useful for studying the dynamics of the seeding of biomaterials.

ORAI1-mediated calcium influx is required for human cytotoxic lymphocyte degranulation and target cell lysis.

Lymphocytes mediate cytotoxicity by polarized release of the contents of cytotoxic granules toward their target cells. Here, we have studied the role of the calcium release-activated calcium channel ORAI1 in human lymphocyte cytotoxicity. Natural killer (NK) cells obtained from an ORAI1-deficient patient displayed defective store-operated Ca(2+) entry (SOCE) and severely defective cytotoxic granule exocytosis leading to impaired target cell lysis. Similar findings were obtained using NK cells from a stromal interaction molecule 1-deficient patient. The defect occurred at a late stage of the signaling process, because activation of leukocyte functional antigen (LFA)-1 and cytotoxic granule polarization were not impaired. Moreover, pharmacological inhibition of SOCE interfered with degranulation and target cell lysis by freshly isolated NK cells and CD8(+) effector T cells from healthy donors. In addition to effects on lymphocyte cytotoxicity, synthesis of the chemokine macrophage inflammatory protein-1ß and the cytokines TNF-α and IFN-γ on target cell recognition was impaired in ORAI1-deficient NK cells, as previously described for T cells. By contrast, NK cell cytokine production induced by combinations of IL-12, IL-15, and IL-18 was not impaired by ORAI1 deficiency. Taken together, these results identify a critical role for ORAI1-mediated Ca(2+) influx in granule exocytosis for lymphocyte cytotoxicity as well as for cytokine production induced by target cell recognition.

Isolation and Characterization of Extracellular Vesicles from Keratinocyte Cultures.

Extracellular vesicles (EVs), including exosomes, are nano-sized membrane-bound particles which are released by cells. They have been found in all examined body fluids and can be isolated from conditioned cell culture media. These vesicles have gained increasing attention due to their importance in cellular cross talk, in both health and disease. For example, keratinocyte-derived EVs have been described to modulate melanin production in epidermis. Similar EVs were also shown to have an important role in skin immunology, by stimulating dendritic cells. In this chapter, we will describe how to isolate EVs from keratinocyte cultures and how to perform characterization by Western blot, nanoparticle tracking analysis, and transmission electron microscopy.

Correction to: Isolation and Characterization of Extracellular Vesicles from Keratinocyte Cultures.

The original version of this chapter was inadvertently published with incorrect spelling of surname of the authors. The names should read Sebastian Sjöqvist, Aya Imafuku, Danu Gupta, and Samir EL Andaloussi, and not Sebastian Sjöqvist, Aya Imafuku, Dhanu Ghupta, and Samir E. L. Andaloussi.

Exosomes derived from clinical-grade oral mucosal epithelial cell sheets promote wound healing.

The oral mucosa exhibits unique regenerative properties, sometimes referred to as foetal-like wound healing. Researchers from our institute have used sheets of oral mucosa epithelial cells (OMECs) for regenerative medicine applications including cornea replacement and oesophageal epithelial regeneration for stricture prevention. Here, we have isolated exosomes from clinical-grade production of OMEC sheets from healthy human donors (n = 8), aiming to evaluate the clinical potential of the exosomes to stimulate epithelial regeneration and to improve understanding of the mode-of-action of the cells. Exosomes were isolated from conditioned (cExo) and non-conditioned (ncExo) media. Characterization was performed using Western blot for common exosomal-markers: CD9 and flotillin were positive while annexin V, EpCam and contaminating marker GRP94 were negative. Nanoparticle tracking analysis revealed a diameter of ~120 nm and transmission electron microscopy showed a corresponding size and spherical appearance. Human skin fibroblasts exposed to exosomes showed dose-dependent reduction of proliferation and a considerable increase of growth factor gene expression (HGF, VEGFA, FGF2 and CTGF). The results were similar for both groups, but with a trend towards a larger effect from cExo. To study adhesion, fluorescently labelled exosomes were topically applied to pig oesophageal wound-beds ex vivo and subsequently washed. Positive signal could be detected after as little as 1 min of adhesion, but increased adhesion time produced a stronger signal. Next, labelled exosomes were added to full-thickness skin wounds in rats and signal was detected up to 5 days after application. cExo significantly reduced the wound size at days 6 and 17. In conclusion, exosomes from OMEC sheets showed pro-regenerative effects on skin wound healing. This is the first time that the healing capacity of the oral mucosa is studied from an exosome perspective. These findings might lead to a combinational therapy of cell sheets and exosomes for future patients with early oesophageal cancer.

Publisher Correction: Experimental orthotopic transplantation of a tissue-engineered oesophagus in rats.

This corrects the article DOI: 10.1038/ncomms4562.

The Use of Mathematical Modelling for Improving the Tissue Engineering of Organs and Stem Cell Therapy.

Regenerative medicine is a multidisciplinary field where continued progress relies on the incorporation of a diverse set of technologies from a wide range of disciplines within medicine, science and engineering. This review describes how one such technique, mathematical modelling, can be utilised to improve the tissue engineering of organs and stem cell therapy. Several case studies, taken from research carried out by our group, ACTREM, demonstrate the utility of mechanistic mathematical models to help aid the design and optimisation of protocols in regenerative medicine.

Quantitative uptake of colloidal particles by cell cultures.

The use of nanotechnologies involving nano- and microparticles has increased tremendously in the recent past. There are various beneficial characteristics that make particles attractive for a wide range of technologies. However, colloidal particles on the other hand can potentially be harmful for humans and environment. Today, complete understanding of the interaction of colloidal particles with biological systems still remains a challenge. Indeed, their uptake, effects, and final cell cycle including their life span fate and degradation in biological systems are not fully understood. This is mainly due to the complexity of multiple parameters which need to be taken in consideration to perform the nanosafety research. Therefore, we will provide an overview of the common denominators and ideas to achieve universal metrics to assess their safety. The review discusses aspects including how biological media could change the physicochemical properties of colloids, how colloids are endocytosed by cells, how to distinguish between internalized versus membrane-attached colloids, possible correlation of cellular uptake of colloids with their physicochemical properties, and how the colloidal stability of colloids may vary upon cell internalization. In conclusion three main statements are given. First, in typically exposure scenarios only part of the colloids associated with cells are internalized while a significant part remain outside cells attached to their membrane. For quantitative uptake studies false positive counts in the form of only adherent but not internalized colloids have to be avoided. pH sensitive fluorophores attached to the colloids, which can discriminate between acidic endosomal/lysosomal and neutral extracellular environment around colloids offer a possible solution. Second, the metrics selected for uptake studies is of utmost importance. Counting the internalized colloids by number or by volume may lead to significantly different results. Third, colloids may change their physicochemical properties along their life cycle, and appropriate characterization is required during the different stages.

Transplantation of tissue-engineered cell sheets for stricture prevention after endoscopic submucosal dissection of the oesophagus.

BACKGROUND AND OBJECTIVE: Endoscopic mucosal dissection (ESD) is a treatment option for oesophagus tumours localized to the mucosa enabling en bloc removal of large lesions. The resulting larger mucosal defects have resulted in an increase in the occurrence of post-treatment strictures. Transplantation of autologous cell sheets, cultured from oral mucosa, has been shown to prevent post-ESD strictures. The aim of the study was to assess the efficacy and safety of cell sheet transplantation after oesophageal ESD in a Western patient population where reflux-associated pre-malignant and malignant conditions predominate. METHODS: Patients with Barrett's oesophagus associated high-grade dysplasia or early adenocarcinoma where ESD entailed a resection >3 cm in length and ≥75% of the circumference were eligible for treatment under hospital exemption. Cell sheets were cultured from buccal mucosa according to Good Manufacturing Practice and were endoscopically applied to the post-ESD defect directly after resection. Patients were followed with weekly endoscopy examinations, including confocal laser microscopy, for a total of four weeks. RESULTS: Five patients were treated. ESD was extensive with resections being circumferential in three patients and 9-10 cm in length in two. The number of transplanted cell sheets ranged from two to six. Three patients developed strictures requiring two to five dilatation sessions. CONCLUSIONS: Cell sheet transplantation shows to be safe and feasible in a Western population. Results suggest that transplantation has a protective effect on the mucosal defect after ESD, decreasing both the risk for and extent of stricture formation.

Orthotopic transplantation of a tissue engineered diaphragm in rats.

The currently available surgical options to repair the diaphragm are associated with significant risks of defect recurrence, lack of growth potential and restored functionality. A tissue engineered diaphragm has the potential to improve surgical outcomes for patients with congenital or acquired disorders. Here we show that decellularized diaphragmatic tissue reseeded with bone marrow mesenchymal stromal cells (BM-MSCs) facilitates in situ regeneration of functional tissue. A novel bioreactor, using simultaneous perfusion and agitation, was used to rapidly decellularize rat diaphragms. The scaffolds retained architecture and mechanical properties and supported cell adhesion, proliferation and differentiation. Biocompatibility was further confirmed in vitro and in vivo. We replaced 80% of the left hemidiaphragm with reseeded diaphragmatic scaffolds. After three weeks, transplanted animals gained 32% weight, showed myography, spirometry parameters, and histological evaluations similar to native rats. In conclusion, our study suggested that reseeded decellularized diaphragmatic tissue appears to be a promising option for patients in need of diaphragmatic reconstruction.

Tracheal tissue engineering in rats.

Tissue-engineered tracheal transplants have been successfully performed clinically. However, before becoming a routine clinical procedure, further preclinical studies are necessary to determine the underlying mechanisms of in situ tissue regeneration. Here we describe a protocol using a tissue engineering strategy and orthotopic transplantation of either natural decellularized donor tracheae or artificial electrospun nanofiber scaffolds into a rat model. The protocol includes details regarding how to assess the scaffolds' biomechanical properties and cell viability before implantation. It is a reliable and reproducible model that can be used to investigate the crucial aspects and pathways of in situ tracheal tissue restoration and regeneration. The model can be established in <6 months, and it may also provide a means to investigate cell-surface interactions, cell differentiation and stem cell fate.