Comparing human and mouse salivary glands: A practice guide for salivary researchers.

Mice are a widely utilized in vivo model for translational salivary gland research but must be used with caution. Specifically, mouse salivary glands are similar in many ways to human salivary glands (i.e., in terms of their anatomy, histology, and physiology) and are both readily available and relatively easy and affordable to maintain. However, there are some significant differences between the two organisms, and by extension, the salivary glands derived from them must be taken into account for translational studies. The current review details pertinent similarities and differences between human and mouse salivary glands and offers practical guidelines for using both for research purposes.

Generation of orthotopically functional salivary gland from embryonic stem cells.

Organoids generated from pluripotent stem cells are used in the development of organ replacement regenerative therapy by recapitulating the process of organogenesis. These processes are strictly regulated by morphogen signalling and transcriptional networks. However, the precise transcription factors involved in the organogenesis of exocrine glands, including salivary glands, remain unknown. Here, we identify a specific combination of two transcription factors (Sox9 and Foxc1) responsible for the differentiation of mouse embryonic stem cell-derived oral ectoderm into the salivary gland rudiment in an organoid culture system. Following orthotopic transplantation into mice whose salivary glands had been removed, the induced salivary gland rudiment not only showed a similar morphology and gene expression profile to those of the embryonic salivary gland rudiment of normal mice but also exhibited characteristics of mature salivary glands, including saliva secretion. This study suggests that exocrine glands can be induced from pluripotent stem cells for organ replacement regenerative therapy.

Combination of submandibular salivary gland transfer and intensity-modulated radiotherapy to reduce dryness of mouth (xerostomia) in patients with head and neck cancer.

BACKGROUND: Xerostomia is a debilitating side effect of radiotherapy for head and neck cancer. Combining surgical submandibular-gland transfer (SMGT) with intensity-modulated radiotherapy (IMRT) may provide greater protection of salivary function. METHODS: This was a single-institution, prospective phase II feasibility trial. Patients with head and neck cancer or unknown primary with neck node metastases received primary surgery with SMGT and postoperative radiotherapy with tomotherapy (60 Gy in 30 fractions). Toxicity and quality of life (QOL) were assessed before surgery, before RT, and after RT. RESULTS: Forty patients received SMGT and IMRT. Only 1 patient experienced grade 3 salivary gland toxicity. At 12 months post-RT, the rate of absent or only mild xerostomia was 89%, and salivary flow rates were approximately 75% of pre-RT levels. CONCLUSIONS: The combination of IMRT with SMGT is feasible and with improved dose constraints may maximally spare the parotid and submandibular glands, leading to decreased xerostomia and improved patient QOL.

Labial Salivary Gland Transplantation for Severe Dry Eye in a Rhesus Monkey Model.

Purpose: To evaluate the effectiveness of autologous labial salivary gland with labial mucous membrane graft in a rhesus monkey model with severe dry eye. Methods: Eight eyes of eight rhesus monkeys with severe dry eye were included. Four eyes underwent autologous labial salivary gland and mucous membrane graft (group 1) and four eyes served as controls (group 2). The ocular surface was evaluated before and after transplantation surgery (at 1, 4, 8, 12, and 24 weeks). Conjunctival impression cytology was performed before and 24 weeks after transplantation. Finally, a histological analysis of the cornea, conjunctiva, and transplanted grafts was performed. Results: At inclusion (n = 8) the mean Schirmer test was 1.31 ± 0.53 mm, the mean fluorescein score was 4.7 ± 1.65, and the mean lissamine green staining was 4.38 ± 0.48. After transplantation, a significant increase in tear secretion was observed with the mean Schirmer test results in group 2 significantly higher than those observed for group 1 at all time points (P < 0.05). Similarly, fluorescein and lissamine green scores were significantly lower in group 2 than in group 1 at all time points after transplantation (P < 0.05). Impression cytology specimens showed severe conjunctival squamous metaplasia without goblet cells in both groups. Under light microscopy, no significant difference was observed between the cornea and the conjunctiva of the two groups. Conclusions: Labial salivary gland transplantation provided a basal secretion of tears and improved ocular surface staining scores during the first 3 months in a severe rhesus monkey model of dry eye. However, this was not accompanied by major improvement of ocular surface tissues.Chinese Abstract.

Survival and quality of life in oropharyngeal cancer patients treated with primary chemoradiation after salivary gland transfer.

OBJECTIVES: Salivary gland transfer surgery can reduce xerostomia in oropharyngeal squamous cell carcinoma patients undergoing primary chemoradiation. A potential drawback of salivary gland transfer is the treatment delay associated with the surgery, and its complications. This study aimed to determine whether the treatment delay affects patient survival and to evaluate patient quality of life after salivary gland transfer. METHODS: A retrospective analysis of 138 patients (salivary gland transfer group, n = 58; non-salivary gland transfer group, n = 80) was performed. Patient survival was compared between these groups using multivariate analysis. Salivary gland transfer patients were further evaluated for surgical complications and for quality of life using the head and neck module of the European Organization for Research and Treatment of Cancer Quality of Life Questionnaire. RESULTS: Salivary gland transfer and non-salivary gland transfer patients had comparable baseline clinical characteristics. Salivary gland transfer patients experienced a median treatment delay of 16.5 days before chemoradiation (p = 0.035). Multivariate analysis showed that this did not, however, correspond to a survival disadvantage (p = 0.24 and p = 0.97 for disease-free and disease-specific survival, respectively). A very low complication rate was reported for the salivary gland transfer group (1.7 per cent). Questionnaire scores for the item 'xerostomia' were very low in salivary gland transfer patients. CONCLUSION: The treatment delay associated with salivary gland transfer surgery does not negatively affect patient survival. Oropharyngeal squamous cell patients have an excellent quality of life after salivary gland transfer.

Management of the Salivary Glands and Facial Nerve in Face Transplantation.

BACKGROUND: Since the first face transplant in 2005, 35 cases have been performed worldwide with acceptable graft survival and satisfactory return of function and appearance. With increasing experience, it is emerging that the salivary glands can contribute to the challenges encountered in the perioperative period. METHODS: A comprehensive review of the literature regarding management of the salivary glands and facial nerve in facial transplantation was performed. Data gathered included inclusion or exclusion of submandibular and parotid glands in the recipient and allograft, extent of mucosal inclusion in the allograft, salivary complications and treatment, level and method of facial nerve repair, and motor nerve outcomes. RESULTS: Information on salivary gland management was available for 25 cases. Undesirable salivary events were documented in 12 cases (48 percent). The source of complications was the parotid in five cases (42 percent), a combination of the parotid and submandibular glands in three cases (25 percent), and minor salivary glands in four cases (33 percent). Postoperative botulinum toxin injections resolved salivary collections in four cases. Facial nerve continuity was restored at the level of the trunk/primary divisions (66 percent) or the terminal branches (34 percent), with inclusion of the whole parotid dictating a trunk repair and exclusion of the parotid dictating a terminal branch repair. CONCLUSIONS: The salivary glands warrant increased attention in surgical planning and postoperative care. Exclusion of the salivary glands from the facial allograft with repair of the terminal branches of the facial nerve appears to be preferable. Botulinum toxin should be considered for prophylaxis and treatment of salivary collections. CLINICAL QUESTION/LEVEL OF EVIDENCE: Therapeutic, V.

Human Salivary Gland Stem Cells Functionally Restore Radiation Damaged Salivary Glands.

Adult stem cells are often touted as therapeutic agents in the regenerative medicine field, however data detailing both the engraftment and functional capabilities of solid tissue derived human adult epithelial stem cells is scarce. Here we show the isolation of adult human salivary gland (SG) stem/progenitor cells and demonstrate at the single cell level in vitro self-renewal and differentiation into multilineage organoids. We also show in vivo functionality, long-term engraftment, and functional restoration in a xenotransplantation model. Indeed, transplanted human salisphere-derived cells restored saliva production and greatly improved the regenerative potential of irradiated SGs. Further selection for c-Kit expression enriched for cells with enhanced regenerative potencies. Interestingly, interaction of transplanted cells with the recipient SG may also be involved in functional recovery. Thus, we show for the first time that salispheres cultured from human SGs contain stem/progenitor cells capable of self-renewal and differentiation and rescue of saliva production. Our study underpins the therapeutic promise of salisphere cell therapy for the treatment of xerostomia.

Reconstitution of a bioengineered salivary gland using a three-dimensional cell manipulation method.

One concept in regenerative therapy is the replacement of a lost or damaged organ with a regenerated, fully functional organ. Three-dimensional cell manipulation techniques, designated "organ germ methods," enable the normal development of a bioengineered organ germ in several types of ectodermal organs, such as teeth, hair follicles, and secretory glands. This method is useful for both organ regeneration technology and developmental biology, including cell kinetic analysis and the elucidation of gene regulation during organogenesis. Here, we describe a protocol for salivary gland reconstitution using the organ germ method to transplant a bioengineered salivary gland germ.

Transplante de glândulas salivares labiais no tratamento de olho seco em cães pela autoenxertia / Labial salivary glands transplantation in the treatment of dry eye in dogs by autograft

OBJETIVO: Avaliar os efeitos clínicos da secreção das glândulas salivares labiais como alternativa de lubrificação ocular para alívio do olho seco, em casos moderados, severos e refratários ao tratamento clínico, através da técnica de transposição de glândulas salivares labiais para o fórnice conjuntival pela autoenxertia. MÉTODOS: Foram selecionados 17 cães os quais apresentavam olho seco autoimune sem reposta satisfatória ao tratamento clínico. O teste lacrimal de Schirmer e o tempo de ruptura do filme lacrimal foram realizados no pré-operatório para avaliar a quantidade e a qualidade da lágrima produzida. Os pacientes foram submetidos aos exames oftálmicos completos no pré-operatório, a cada 15 dias por dois meses e a cada 30 dias por mais dois meses, totalizando seis retornos pós-operatórios. No pré-operatório e em todos os pós-operatórios fotografias digitais foram tiradas para o arquivo fotográfico. Utilizou-se o programa photoshop para avaliação e marcação dos neovasos corneanos em todos os retornos. RESULTADOS: Houve redução em todos os casos da secreção mucopurulenta, hiperemia conjuntival e blefarospasmo, bem como estabilização de lesões pré-existentes e redução importante do número de neovasos corneanos. A transposição resultou na melhora do tempo de ruptura do filme lacrimal, porém sem alterações significativas no teste de Schirmer. CONCLUSÃO: O transplante das glândulas salivares labiais para o fórnice conjuntival é um procedimento de fácil execução, rápido, eficaz, acessível a qualquer cirurgião veterinário oftalmologista e de grande valia para casos moderados e severos de ceratoconjuntivite seca não responsivos às medicações existentes.

OBJECTIVE: To evaluate the clinical effects of lips salivary gland secretion as ocular lubricant for dry eye relief in mild cases, severe and refractory to medical treatment, through the transposition technique of salivary glands autograft to the conjunctival fornix. METHODS: Seventeen dogs exhibiting autoimmune dry eye with no satisfactory response to clinical treatment were selected. Lacrimal Schirmer Test and Tear Film break-up time (BUT) preoperative tests were performed to estimate the quantity and the quality of produced tear. Animals were submitted to complete ophthalmic exams routine preoperative, each 15 days for two months and then each 30 days for more two months after surgery, totalizing six returns. Photos were taken before and after surgical procedure for photo archive. Photoshop software was utilized for corneal neovascular evaluation. RESULTS: Mucopurulent secretion, conjunctival hyperemia and blepharospasm diminished in all cases, as well as occurred stabilization of pre existent damages with important reduction of corneal neovascularization. The transposition resulted on break-up time tests improvement but no significant changes on Schirmer tests. CONCLUSION: This technique is simple, quick and effective, accessible to any veterinary ophthalmologist surgeon and is of great value for moderate and severe cases of dry keratoconjunctivitis not responsive to medications.

Functional transplantation of salivary gland cells differentiated from mouse early ES cells in vitro.

Atrophy or hypofunction of the salivary gland because of aging or disease causes hyposalivation and has an effect on the quality of life of patients, for example not only dry mouth but deterioration in mastication/deglutition disorder and the status of oral hygiene. Currently conducted therapies for atrophy or hypofunction of the salivary gland in clinical practice are only symptomatic treatments with drugs and artificial saliva, and therefore it is preferable to establish a radical therapy. At this time, as a fundamental investigation, by co-culturing mouse early ES (mEES-6) cells with human salivary gland-derived fibroblasts (hSG-fibro), differentiation of mEES-6 cells to salivary gland cells has been attempted. Also, the possibility of cell engraftment was examined. After identifying the cells which were co-cultured with GFP-transfected mEES-6 cells and hSG-fibro, the cells were transplanted into the submandibular gland of SCID mice, and the degree of differentiation into tissues was examined. The possibility of tissue functional reconstitution from co-cultured cells in a three-dimensional culture system was examined. Our results confirmed that the co-cultured cells expressed salivary gland-related markers and had an ability to generate neo-tissues by transplantation in vivo. Moreover, the cells could reconstitute gland structures in a three-dimensional culture system. By co-culture with hSG-fibro, mEES-6 cells were successfully differentiated into salivary gland cells which were transplantable and have tissue neogenetic ability.

[Transplantation of autologous labial salivary glands for severe dry eye].

OBJECTIVE: Autologous labial salivary gland transplantation has been a promising alternative for the treatment of severe dry eye. In this article, we describe the results of the ocular surface changes after labial salivary gland transplantation and investigate the feasibility of this treatment. METHODS: The results of this technique in 8 patients (eyes) who suffered from severe dry eye were prospectively analyzed after surgery (follow-up of 6 months). The best-corrected visual acuity, Schirmer I test, degree of discomfort, usage of pharmaceutical tear substitutes, tear interferometry and slit lamp examination were investigated at different time before and after surgery. RESULTS: All grafts remained viable and the survival rate is 100%. All patients showed significant increase in the Schirmer's test and they expressed great improvement in their ocular discomfort. The use of artificial tear substitutes was reduced because of the increased ocular surface lubrication. CONCLUSION: Although the authors' long-term experience still is limited, we believe that the procedure is a promising alternative approach for severe dry eye.

Cell therapy for salivary gland regeneration.

There are still no effective therapies for hyposalivation caused by irradiation. In our previous study, bone marrow stem cells can be transdifferentiated into acinar-like cells in vitro. Therefore, we hypothesized that transplantation with bone marrow stem cells or acinar-like cells may help functional regeneration of salivary glands. Bone marrow stem cells were labeled with nanoparticles and directly co-cultured with acinar cells to obtain labeled acinar-like cells. In total, 140 severely combined immune-deficiency mice were divided into 4 groups for cell therapy experiments: (1) normal mice, (2) mice receiving irradiation around their head-and-neck areas; (3) mice receiving irradiation and intra-gland transplantation with labeled stem cells; and (4) mice receiving irradiation and intra-gland transplantation with labeled acinar-like cells. Our results showed that salivary glands damaged due to irradiation can be rescued by cell therapy with either bone marrow stem cells or acinar-like cells for recovery of saliva production, body weight, and gland weight. Transdifferentiation of bone marrow stem cells into acinar-like cells in vivo was also noted. This study demonstrated that cell therapy with bone marrow stem cells or acinar-like cells can help functional regeneration of salivary glands, and that acinar-like cells showed better therapeutic potentials than those of bone marrow stem cells.

Labial salivary gland transplantation for severe dry eye due to chemical burns and Stevens-Johnson syndrome.

PURPOSE: Salivary gland transplantation has been a promising alternative for the treatment of dry eye syndrome. In this article, we describe the results of an autotransplant procedure of labial salivary glands in the upper conjunctival fornix of patients with severe dry eye. METHODS: A total of 14 eyes from 14 patients presenting with Stevens-Johnson syndrome and chemical burns were prospectively analyzed after surgery (average follow-up of 14 months). We evaluated their underlying symptoms, visual acuity, biomicroscopy, Schirmer's test, break-up time, and need for lubricants before and after transplantation. RESULTS: All patients expressed improvement in their ocular discomfort. Nine eyes showed a slight best-corrected visual acuity improvement, while the vision of the remainder stayed stable. Corneal staining, present in all patients before surgery, was persistent in only four patients, but in a reduced area. Schirmer's test and break-up time showed significant increase in all patients (p < 0.05). In 71% of the patients, the use of lubricants was reduced. CONCLUSION: Labial salivary gland transplantation can improve the life quality of patients with compromised ocular surfaces who suffer from severe dry eye syndrome.

Current status of the development of an artificial salivary gland.

Salivary glands (SGs) secrete more than half a liter of saliva daily. Saliva has many functions in maintaining the normal homeostasis of the oral cavity. Several causes underlie salivary impairment, where irradiation therapy to head and neck cancer patients is one of the most debilitating causes leading to considerable decrease in the patients' quality of life. In the last decade, others and we have focused on implementing tissue engineering principles combined with gene transfer and stem cell methodologies to develop an artificial SG device. This manuscript provides an overview of the current status of engineering an artificial SG.

[Radiation-induced xerostomia: prevention, treatment, perspectives]. / Xérostomie radio-induite: prevéntion, traitement, perspectives.

Most of head and neck cancer patients will undergo radiotherapy. Xerostomia is probably its most frequent side effect. Subjective and objective criteria allow evaluating and grading xerostomia. New radiotherapy techniques and use of cytoprotectants can help to preserve salivary gland function. Parasym-pathicomimetics and saliva substitutes reduce symptoms. Strict mouth cleaning and fluoride's use prevent teeth deterioration and infections. Important breakthroughs have been made in the pathophysiology of xerostomia and new treatments are developed.

Management of salivary hypofunction during and after radiotherapy.

Salivary hypofunction, the most common complication of high-dose radiation therapy (RT) to the head and neck, has a significant impact on quality of life, and requires careful planning of long-term dental and oral care. This report documents the results and conclusions of an evidence-based literature review on multidisciplinary team management of salivary hypofunction during and after RT. An update is provided on the pathophysiology of salivary hypofunction during and after RT, and recommendations for clinical management. The paper presents aspects managed by dental professionals (use of cholinergic agonists and other saliva stimulants, prevention of hyposalivation-induced rampant caries, and use of saliva substitutes), as well as the role of the radiation oncologist in minimizing salivary gland damage (parotid-sparing RT; cytoprotectants). This summary includes basic science, translational and clinical research topics with respect to radiation-induced salivary hypofunction, and provides an evidence-based management algorithm.

Adnexal surgery for severe ocular surface disease.

Secondary causes of ocular surface disease are-to a large extent-due to disorders of the ocular adnexae. The main pathomechanisms involved include exposure, abrasion and malnutrition, resulting from a multitude of disorders such as ec- or entropion (e.g. in cicatrizing conjunctivitis), lid retraction and severe aqueous deficiency. In the presence of these problems, surgical attempts of ocular surface reconstruction frequently fail. Here we review established and evolving new techniques in the field of adnexal surgery to specifically address these problems.

Characterization of murine autologous salivary gland graft cells: a model for use with an artificial salivary gland.

The purpose of this study was to examine the growth and key functional abilities of primary cultures of salivary epithelial cells toward developing an artificial salivary gland. Cultures of epithelial cells originating from submandibular glands of BALB/c mice were established. Parenchymal cells were isolated by a Percoll gradient technique and thereafter seeded on irradiated NIH 3T3 fibroblasts serving as a feeder layer. The isolated cells were termed autologous salivary gland epithelial (ASGE) cells and could be cultivated for at least five passages (time limit of experiments). ASGE cells presented the typical organizational behavior of epithelial cells and electron microscopy, as well as immunostaining for cytokeratins, confirmed their epithelial origin. Furthermore, measurements of transepithelial resistance and water permeability indicated the ability of the ASGE cells to form a functional epithelial barrier. This study suggests that primary salivary epithelial cells can be obtained that exhibit critical characteristics needed for use with an artificial secretory device.

The patient with xerostomia: medical therapy, prosthetic therapy.

The condition of xerostomia has significant consequences on both the hard and the soft components of the oral cavity, and can compromise functionality. Furthermore, this clinical complication produces negative changes in eating habits, frequently causing the loss of several kilograms of body weight. This article aims to provide as complete as possible an overview of therapeutic possibilities. Alongside medical therapy, the article will report on an experimental treatment designed for patients who are scheduled for radiation therapy to an area including a major salivary gland (in particular the parotid gland). The treatment consists in autologous transplantation of a portion of glandular tissue to a site outside the irradiated area. Lastly, a particular method for prosthetic rehabilitation, the so-called "reservoir" denture, is presented. A complete denture is produced with conventional techniques but has a small container for artificial saliva. For mandibular dentures the container is sub-divided into 3 inter-communicating chambers and is situated in the lingual flange; for maxillary dentures, a single chamber is situated in the palatine concavity. In our opinion, the mandibular reservoir denture presented here has better characteristics than other devices that have been reported in the international literature.