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.

How to resolve confusion in the clinical setting for the diagnosis of heterozygous COL4A3 or COL4A4 gene variants? Discussion and suggestions from nephrologists.

Both thin basement membrane nephropathy (TBMN) and autosomal dominant Alport syndrome (ADAS) are types of hereditary nephritis resulting from heterozygous mutations in COL4A3 or COL4A4 genes. Although TBMN is characterized by hematuria and thinning of the glomerular basement membrane (GBM) with excellent renal prognosis, some patients develop end-stage renal disease (ESRD) later in life. In contrast, although AS is characterized by progressive nephropathy with lamellation of the GBM, there are some patients diagnosed with ADAS from a family history of ESRD but who only suffer from hematuria with GBM thinning. These findings indicate a limitation in distinction between TBMN and ADAS. Diagnosis of AS is significant because it facilitates careful follow-up and early treatment, whereas diagnosis of TBMN can underestimate the risk of ESRD. However, some experts are against using the term ADAS as the phenotypes of heterozygous variants vary from no urinary abnormality to ESRD, even between family members with the same mutations, indicating that unknown secondary factors may play a large role in the disease severity. These diagnostic difficulties result in significant confusion in clinical settings. Moreover, recent studies revealed that the number of patients with chronic kidney disease caused by these gene mutations is far higher than previously thought. The aim of this article is to review differing opinions regarding the diagnosis of heterozygous COL4A3 or COL4A4 variants, and to highlight the importance for nephrologists to recognize this disease, and the importance of the need to reclassify this disease to minimize the current confusion.

Significance of urinary albumin excretion in patients with cast nephropathy
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BACKGROUND: This study was performed to determine whether the urinary albumin excretion rate (%UAE) could distinguish myeloma cast nephropathy (MCN) without glomerular amyloid deposition from MCN with glomerular amyloid deposition. MATERIALS AND METHODS: We retrospectively reviewed clinicopathological data on 16 patients with MCN diagnosed by renal biopsy at Toranomon Hospital from 2004 to 2014. RESULTS: A total of 10 patients had pure MCN without glomerular amyloid deposition (group 1), and 6 patients had MCN with glomerular amyloid deposition (group 2). In all 10 patients from group 1, the underlying disease was multiple myeloma (MM), while 4 patients had MM, and 2 patients had lymphoplasmacytic lymphoma/Waldenström macroglobulinemia (LPL/WM) in group 2. Total protein did not show a significant difference between the two groups, but serum albumin was significantly higher in group 1 than group 2 (p = 0.0101). Serum-adjusted calcium did not show a significant difference between the groups, while serum creatinine (Cre) was significantly higher in group 1 than group 2 (p = 0.0343). Although urinary protein excretion did not differ significantly between the groups, the %UAE was significantly lower in group 1 than group 2 (p = 0.00198). In group 2, 3 of the 4 patients with MM died within 15 months of diagnosis, but the 2 patients with LPL/WM are alive after 32 months. In group 1, only 1 patient died (of unknown causes) within 15 months after diagnosis. CONCLUSION: In patients with MCN, %UAE may be a useful marker for the detection of coexistence of glomerular lesions, such as amyloidosis, which are associated with a poor outcome.

Detection of Splicing Abnormalities and Genotype-Phenotype Correlation in X-linked Alport Syndrome.

BACKGROUND: X-linked Alport syndrome (XLAS) is a progressive hereditary nephropathy caused by mutations in the COL4A5 gene. Genotype-phenotype correlation in male XLAS is relatively well established; relative to truncating mutations, nontruncating mutations exhibit milder phenotypes. However, transcript comparison between XLAS cases with splicing abnormalities that result in a premature stop codon and those with nontruncating splicing abnormalities has not been reported, mainly because transcript analysis is not routinely conducted in patients with XLAS. METHODS: We examined transcript expression for all patients with suspected splicing abnormalities who were treated at one hospital between January of 2006 and July of 2017. Additionally, we recruited 46 males from 29 families with splicing abnormalities to examine genotype-phenotype correlation in patients with truncating (n=21, from 14 families) and nontruncating (n=25, from 15 families) mutations at the transcript level. RESULTS: We detected 41 XLAS families with abnormal splicing patterns and described novel XLAS atypical splicing patterns (n=14) other than exon skipping caused by point mutations in the splice consensus sequence. The median age for developing ESRD was 20 years (95% confidence interval, 14 to 23 years) among patients with truncating mutations and 29 years (95% confidence interval, 25 to 40 years) among patients with nontruncating mutations (P=0.001). CONCLUSIONS: We report unpredictable atypical splicing in the COL4A5 gene in male patients with XLAS and reveal that renal prognosis differs significantly for patients with truncating versus nontruncating splicing abnormalities. Our results suggest that splicing modulation should be explored as a therapy for XLAS with truncating mutations.

Risk factors of ceftriaxone-associated biliary pseudolithiasis in adults: influence of renal dysfunction.

BACKGROUND: Ceftriaxone (CTRX) is a known cause of biliary pseudolithiasis (BPL) mainly in children. Biliary elimination of CTRX increases in patients with renal dysfunction. However, the influence of renal dysfunction on the incidence of CTRX-associated BPL has not been well investigated. The aim of this study was to investigate the cumulative incidence of CTRX-associated BPL in adults and to assess if renal dysfunction is a risk factor. METHODS: We retrospectively analyzed the medical records of 478 patients treated with CTRX to assess the incidence and risk factors of CTRX-associated BPL. We examined age, sex, body weight, dosage, and duration of CTRX therapy, and the concentrations of serum creatinine, estimated glomerular filtration rate (eGFR), albumin, and serum calcium in all the patients. The cumulative incidence of BPL was calculated using a competing risk model. The multivariate analysis of each variable for the development of BPL was assessed by a Cox proportional hazards model. RESULTS: A total of 362 patients (75.7%) had renal dysfunction (eGFR: < 60 mL/min). The cumulative incidence of BPL in patients with renal dysfunction was significantly higher than that in patients with normal kidney function (4.1 vs. 0.6%, p = 0.017). Renal dysfunction (Hazard ratio (HR) 8.14, 95% CI 1.05-63.0, p = 0.045) and female sex (HR 5.35, 95% CI 1.17-24.5, p = 0.031) were independent risk factors of CTRX-associated BPL, which was confirmed using multivariate analysis (renal dysfunction: HR 7.93, 95% CI 1.04-60.5, p = 0.046) (female sex HR 4.65, 95% CI 1.03-21.1, p = 0.046). CONCLUSIONS: Renal dysfunction is an independent risk factor of CTRX-associated BPL in adults.

Autosomal dominant form of type IV collagen nephropathy exists among patients with hereditary nephritis difficult to diagnose clinicopathologically.

AIM: Type IV collagen nephropathies include Alport Syndrome and thin basement membrane nephropathy (TBMN), which are caused by mutations in COL4A3/A4/A5 genes. Recently, reports of patients with heterozygous mutations in COL4A3/A4 have been increasing. The clinical course of these patients has a wide variety, and they are diagnosed as TBMN, autosomal dominant Alport syndrome (ADAS), or familial focal segmental glomerular sclerosis. However, diagnosis, frequency and clinicopathological manifestation of them remains unclear. We tested COL4A3/A4/A5 genes in patients with hereditary nephritis that was difficult to diagnose clinicopathologically, and investigated who should undergo such testing. METHODS: We performed immunostaining for α5 chain of type IV collagen [α5 (IV)] in 27 patients from 21 families who fitted the following criteria: (i) haematuria and proteinuria (± renal dysfunction); (ii) family history of haematuria, proteinuria, and/or renal dysfunction (autosomal dominant inheritance); (iii) no specific glomerulonephritis; and (iv) thinning, splitting, or lamellation of the glomerular basement membrane (GBM) on electron microscopy. Then we performed genetic testing in 19 patients from 16 families who showed normal α5 (IV) patterns. We conducted a retrospective analysis of their clinicopathological findings. RESULTS: Among 16 families, 69% were detected heterozygous mutations in COL4A3/A4, suggesting the diagnosis of TBMN/ADAS. Twenty-one percent of patients developed end stage renal disease. All patients showed thinning of GBM, which was accompanied by splitting or lamellation in seven patients. CONCLUSION: A considerable fraction of patients with hereditary nephritis that is difficult to diagnose clinicopathologically have TBMN/ADAS. It is important to recognize TBMN/ADAS and perform genetic testing in appropriate patients.

Acquired hemophilia A that developed during the induction of hemodialysis: the use of double-filtration plasmapheresis
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Acquired hemophilia A (AHA) is a rare bleeding disorder caused by autoantibodies to coagulation factor VIII (FVIII). AHA onset during the induction of dialysis is extremely rare, and the management of blood access is difficult. We present a case of AHA that developed during induction of dialysis and treatment with double filtration plasmapheresis (DFPP). An 86-year-old man with chronic kidney disease was admitted to our hospital with multiple subcutaneous hemorrhages. Because of his prolonged activated partial thromboplastin time (aPTT) and high titer of inhibitors to FVIII, he was diagnosed with AHA, and prednisolone treatment was started. After 3 weeks of steroid therapy, his renal function deteriorated, and dialysis was needed. We performed femoral catheter placement under administration of recombinant activated factor VII (rFVIIa) to prevent bleeding. The patient developed catheter-related bloodstream infection and needed arteriovenous fistula (AVF) immediately. After 4 DFPP sessions, his hemostasis recovered to normal. AVF placement did not cause any complication, and he could safely undergo maintenance hemodialysis. Clinicians should suspect AHA in end-stage renal disease patients with acute onset of bleeding and an unexplained prolonged aPTT. DFPP is useful in patients with AHA that develops during induction of dialysis and requires surgical treatment.
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A clinical staging score to measure the severity of dialysis-related amyloidosis.

BACKGROUND: The ongoing effort to prevent dialysis-related amyloidosis (DRA) has been hampered by lack of any way to measure DRA's severity. Yet, such measurement is essential for assessing the effect of DRA treatment. Accordingly, we developed a scoring system focused on the physical manifestations of DRA. METHODS: Forty-four patients on maintenance hemodialysis with DRA, and 96 without it, were enrolled. The SF-36v2 Health Survey ascertained whether patients experienced general bodily pain and/or physical dysfunction with any attendant specific pain (dysfunction). If so, the association of those conditions with a finding of DRA was analyzed-including laboratory and radiographic data-and a scoring system reflecting the extent of that dysfunction was devised using the significant variables in the multivariate analysis. RESULTS: Both dysfunction and general bodily pain were severe in patients with DRA. Presence of polyarthralgia, trigger finger, carpal tunnel syndrome (CTS), and dialysis-related spondyloarthropathy (DRS) were associated with that dysfunction after appropriate adjustments. The new scoring system used those four variables in the model, with a 3 given for polyarthralgia and DRS, and 2 for trigger finger and CTS (possible range 0-10). Based on the physical functioning score of SF-36v2, we categorized A-score into three stages: mild (A-score 3-4), moderate (5-7), and severe (8-10). The corresponding area under the receiver-operating characteristics curve for diagnosis of DRA was 0.9345 when we set the cutoff value as 4. CONCLUSION: This validated scoring system for quantitatively estimating the severity of DRA can serve as A useful measure in clinical practice.

Suitability of Patients with Autosomal Dominant Polycystic Kidney Disease for Renal Transcatheter Arterial Embolization.

In patients with autosomal dominant polycystic kidney disease (ADPKD), massive renal enlargement is a serious problem. Renal transcatheter arterial embolization (TAE) can reduce renal volume (RV), but effectiveness varies widely, and the reasons remain unclear. We investigated factors affecting renal volume reduction rate (RVRR) after renal TAE in all 449 patients with ADPKD who received renal TAE at Toranomon Hospital from January of 2006 to July of 2013, including 228 men and 221 women (mean age =57.0±9.1 years old). One year after renal TAE, the RVRR ranged from 3.9% to 84.8%, and the least squares mean RVRR calculated using a linear mixed model was 45.5% (95% confidence interval [95% CI], 44.2% to 46.8%). Multivariate analysis using the linear mixed model revealed that RVRR was affected by the presence of large cysts with wall thickening (regression coefficient [RC], -6.10; 95% CI, -9.04 to -3.16; P<0.001), age (RC, -0.82; 95% CI, -1.03 to -0.60; P<0.001), dialysis duration (RC, -0.10; 95% CI, -0.18 to -0.03; P<0.01), systolic BP (RC, 0.39; 95% CI, 0.19 to 0.59; P<0.001), and the number of microcoils used for renal TAE (RC, 1.35; 95% CI, 0.83 to 1.86; P<0.001). Significantly more microcoils were needed to achieve renal TAE in patients with younger age and shorter dialysis duration. In conclusion, cyst wall thickening had an important effect on cyst volume reduction. Renal TAE was more effective in patients who were younger, had shorter dialysis duration, or had hypertension, parameters that might associate with cyst wall stiffness and renal artery blood flow.

Intracystic magnetic resonance imaging in patients with autosomal dominant polycystic kidney disease: features of severe cyst infection in a case-control study.

BACKGROUND: The purpose of this study was to investigate the usefulness of intracystic MRI features for detection of severe cyst infection that is usually refractory to antibiotic therapy alone in patients with autosomal dominant polycystic kidney disease. METHODS: Seventy-six patients (88 episodes) with positive cyst cultures treated from January 2006 to December 2013 were enrolled as the cases for this case-control study, while 147 patients who continued to attend our hospital from January 2011 to December 2013 and did not have cyst infection diagnosed during that period were enrolled as the controls. Intracystic MRI findings were investigated. RESULTS: At least one of four intracystic MRI features (high signal intensity (SI) on diffusion-weighted images (DWI), fluid-fluid level, wall thickening, or gas) was found in all of the cases, but such findings were also detected in some controls. Intracystic gas was specific for cyst infection, but its sensitivity was only 1.1 %. A high intracystic SI on DWI showed a sensitivity of 86.4 %, but its specificity was lower at 33.3 %. Both the specificity and sensitivity of a fluid-fluid level or wall thickening were about 80 %. However, the specificity of these MRI features decreased as total liver and kidney volume (TLKV) increased, falling to 65.8 % in patients with organomegaly (TLKV > 8500 cm3). A cyst diameter > 5 cm was useful for detecting severely infected cysts that needed drainage, and specificity was increased by combining the other four MRI findings with a cyst diameter > 5 cm. CONCLUSIONS: MRI with DWI was useful for detecting severe cyst infection in ADPKD. While the specificity of MRI alone was not high enough in patients with organomegaly, combining the four MRI features with abdominal pain, sequential MRI changes, or cyst diameter > 5 cm improved detection of severely infected cysts in these patients.

A pathological scoring system to predict renal outcome in diabetic nephropathy.

BACKGROUND: With the association between diabetic nephropathy (DN) and renal outcome being increasingly clear, we aimed at creating a new DN pathological scoring system that could predict the renal outcome. METHODS: We studied 205 patients with DN confirmed by renal biopsy, sometime between March 1985 and January 2010, who met the inclusion criteria. Renal biopsy included clinical parameters and Tervaert classifications. Hazard ratios (HRs) for death-censored end-stage renal disease (ESRD) were estimated by adjusted Cox proportional-hazards regression. The overall pathological risk score (D-score) was calculated by summing the products of beta coefficient and bootstrap-inclusion fractions, its predictive utility evaluated by Kaplan-Meier methods and c-statistics for a 10-year risk of ESRD. RESULTS: The D-scores of glomerular classes 1, 2A, 2B, 3, and 4 were, respectively, 0, 3, 4, 6, and 6. Those of interstitial fibrosis and tubular atrophy classes 0, 1, 2, and 3 were 0, 7, 9, and 11, and those of interstitial inflammation classes 0, 1, and 2 were 0, 3, and 4, respectively. The D-score of hyalinosis class 2 was 3 and that of arteriosclerosis class 2 was 1. So, a patient's D-score could be 0-25. HRs for ESRD in patients with D-score ≤14, 15-18, 19-21, and 22-25 were, respectively, 1.00 (reference) 16.21 (95% confidence interval (CI), 1.86-140.90), 19.78 (95% CI, 2.15-182.40), and 45.46 (95% CI, 4.63-446.68) after adjusting for clinical factors. The c-statistics suggested a better predictive ability for a 10-year renal death with models that included the D-score. CONCLUSION: Prediction of DN patients' renal outcome was better with the D-score than without it. Patients with a D-score ≤14 had excellent renal prognosis.

[A case of allergic bronchopulmonary mycosis caused by Schizophyllum commune presenting with hyperattenuated mucoid impaction].

A 64-year-old woman was admitted to our hospital because of cough, bloody sputum and chest pain in January 2007. Chest computed tomography (CT) on admission revealed hyperattenuated mucoid impaction and consolidation in the right S3b. She was given a diagnosis of allergic bronchopulmonary mycosis caused by Schizophyllum commune. Treatment with 200 mg/day itraconazole and 15 mg/day oral prednisolone was begun, and her symptoms and consolidation resolved. In December 2007, consolidation in the left lower lobe appeared after itraconazole was stopped and replaced with oral prednisolone with inhaled fluticasone propionate. She again received 200 mg/day itraconazole and 15 mg/day oral prednisolone, resulting in a reduction in her consolidation. In May 2008, itraconazole was stopped and oral prednisolone was changed to inhaled salmeterol fluticasone propionate. In November 2008, her symptoms appeared again, and chest CT demonstrated hyperattenuated mucoid impaction and consolidation in the right S8. A transbronchial biopsy revealed granulomatosis, Charcot-Leyden crystals, and mucus infiltrated by eosinophils and fungi. Schizophyllum commune was isolated from her bronchial lavage fluid. A recurrence of allergic bronchopulmonary mycosis was diagnosed. Retreatment with itraconazole and oral prednisolone resulted in improvement of her symptoms and chest radiographic findings. To the best of our knowledge this is the first reported case of allergic bronchopulmonary mycosis caused by Schizophyllum commune presenting with hyperattenuated mucoid impaction.

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.

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.

Rapidly progressive glomerulonephritis caused by tegafur/gimeracil/oteracil resulted in diabetes nephropathy, in a patient with minor risk of diabetes nephropathy: a case report.

A 79-year-old Japanese male with a history of type 2 diabetes mellitus (T2DM) for 16 years was admitted to evaluate possible renal disease. The T2DM was well controlled in this patient using nutrition therapy without the need for any diabetes medication, and both diabetes retinopathy and proteinuria were negative. At the age of 78 advanced colorectal cancer (stage IIIa) was diagnosed and laparoscopic-assisted colectomy was performed. Following this procedure, the patient began treatment with tegafur/gimeracil/oteracil (S-1), 80 mg twice daily for 28 days of 42-day cycle. The patient received S-1 for 6 months, during which time, serum albumin decreased from 3.0 g/dL to 1.1 g/dL, urinary protein increased from negative to 3.0 g/day, and serum creatinine increased from 0.9 mg/dL to 2.1 mg/dL. Treatment with S-1 was discontinued, and furosemide 180 mg and prednisolone 30 mg treatment was initiated; however, serum creatinine levels continued to increase to 7.2 mg/dL and proteinuria continued to increase reaching a nephrotic range. A disintegrin and metalloproteinase with a thrombospondin type 1 motif, member 13 (ADAMTS13) activity was decreased to 27.0%. Renal biopsy showed Kimmelstiel-Wilson nodules, while immunofluorescence intensity of IgG subclass was IgG1 dominant, which was not compatible with diabetic nephropathy (DN). Plasma exchange was not affected. However, hemodialysis was initiated.The results of this investigation suggest that when S-1 monotherapy is performed in the case with DN, rapidly progressive glomerulonephritis (RPGN) may develop due to a condition similar to thrombotic microangiopathy, even in patients with a minor risk factor of DN.

Rat Mesenchymal Stromal Cell Sheets Suppress Renal Fibrosis via Microvascular Protection.

Renal fibrosis is one of the largest global health care problems, and microvascular (MV) injury is important in the development of progressive fibrosis. Although conventional cell therapy suppresses kidney injury via the role of vasoprotective cytokines, the effects are limited due to low retention of administered cells. We recently described that transplantation of hepatocyte growth factor (HGF)-transgenic mesothelial cell sheets showed a remarkable cell survival and strong therapeutic effects in a rat renal fibrosis model. Due to the translational hurdles of transgenic cells, we here applied this technique for allogeneic transplantation using rat bone marrow mesenchymal stromal cells (MSCs). MSC sheets were transplanted onto the kidney surface of a rat renal ischemia-reperfusion-injury model and the effects were compared between those in untreated rats and those receiving intravenous (IV) administration of the cells. We found that donor-cell survival was superior in the cell sheet group relative to the IV group, and that the cell sheets secreted HGF and vascular endothelial growth factor (VEGF) up to day 14. Transplantation of cell sheets increased the expression of activated HGF/VEGF receptors in the kidney. There was no evidence of migration of transplanted cells into the kidney parenchyma. Additionally, the cell sheets significantly suppressed renal dysfunction, MV injury, and fibrosis as compared with that observed in the untreated and IV groups. Furthermore, we demonstrated that the MSC sheet protected MV density in the whole kidney according to three-dimensional microcomputed tomography. In conclusion, MSC sheets strongly prevented renal fibrosis via MV protection, suggesting that this strategy represents a potential novel therapy for various kidney diseases. Stem Cells Translational Medicine 2019;8:1330&1341.

Incidence and risk factors of new-onset hypertrophic pachymeningitis in patients with anti-neutrophil antibody-associated vasculitis: using logistic regression and classification tree analysis.

OBJECTIVES: Hypertrophic pachymeningitis (HP) is a rare complication in patients with anti-neutrophil antibody-associated vasculitis (AAV); its clinical features, incidence, and risk factors remain unknown. We aimed to clarify the prevalence, clinical features, and factors associated with new-onset HP in patients with AAV. METHOD: A retrospective cohort study involving 93 patients with AAV was conducted. HP incidence between patients with granulomatosis with polyangiitis (GPA) and those with microscopic polyangiitis (MPA) was compared to investigate risk factors associated with HP. We performed only univariate analysis using logistic regression and classification tree (CART) analysis due to the small number of HP cases. RESULTS: Among the 93 patients (76 with MPA and 17 with GPA), only 6 patients developed HP (1 with MPA, 5 with GPA) over an average observation period of 4 years; all patients who developed HP were positive for myeloperoxidase anti-neutrophil antibody. HP incidence was significantly higher in patients with GPA than in those with MPA (60.2 versus 3.3 persons per 1000 person-years, respectively, P = 0.002). The univariate analysis revealed that otitis media (P < 0.001) and sinusitis (P = 0.014) were associated with new-onset HP. Univariate CART analysis grouped the patients into patients with HP who have otitis media (33%) and patients with HP who have sinusitis (21%). The odds ratio of otitis media adjusted by age and first diagnosis of AAV was 38.1 (95% confidence interval, 3.08-331.4; P = 0.004). CONCLUSIONS: Although only in the univariate analysis, otitis media was the most discriminating factor to predict new-onset HP in patients with AAV.

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.