in the first place , a homogeneous polysaccharide suspension of sc is produced : the solution has a 90 % purity in terms of cellular composition and is obtained in a saline solution of ultrapure sodium alginate at a concentration comprised between 1 and 5 % w / v , advantageously between 1 and 3 %. the alginate used is ultrapure as it exhibits an endotoxin content not higher than 20 eu / g and a protein content & lt ; 0 . 4 %; air is advantageously used as fluid . sc are treated in advance with trypsin and edta ( 2 min ), in order to obtain a homogeneous cellular suspension . the following were used to assess it : immunocytochemistry techniques , incubating the preparation with anti - mullerian inhibiting factor ( mis ) and fluorescin anti - vimentin antibodies , which respectively mark the mis and vimentin molecules , both expressed by the sc only . histochemical techniques to assess the presence of both alkaline phosphatase ( colouring with fast - red ) typical of peritubular cell , and of the 3 - β - hydroxy - steroidodehydrogenase enzyme ( colouring with nitro - blue tetrazolium ) which on the other hand is typical of leydig cells . the results obtained with such histochemical assays have allowed to prove the presence of 5 - 8 % of peritubular and leydig cells ; these cellular populations , moreover , are useful ( when present in these proportions ) to ensure a molecular “ cross - talk ” favourable for the correct functionality of sc . this suspension is aspired at a speed comprised between 10 and 60 ml / min producing a continuous flow of dimensionally homogeneous microdroplets through suction and extrusion using a fluid current , advantageously air , at controlled pressure . the suspension thus aspired is introduced in a needle - type element to be divided into highly homogeneous microdroplets . advantageously , the needle - type element exhibits a buttonhole opening on the side surface thereof wherein a fluid current is introduced at a rate of 3 - 7 litres / min to obtain a continuous flow of homogeneous size microdroplets . the fluid current is obtained from a generator and before being used , it is subject to a pressure reduction to obtain a pressure drop in the flow - non flow transient not less than 0 . 3 bar ; to a regulation to obtain high reproducibility in the flow - non flow transient and linearity between number of revolutions and fluid current dispensed , and to a regulation and control of the output current between 0 and 10 nl / min . the microdroplets may have a mean diameter comprised between 300 and 700 μm with a standard deviation below 40 μm . the microdroplets obtained are introduced in an aqueous solution , advantageously using sterilised water for injectable preparations , f . u , containing divalent cations or polycationic substances with resulting gelification and obtainment of said microcapsules . a further object of the present invention are sertoli cells as sole therapeutic agent for the prevention and radical cure of t1dm . advantageously , according to the process of the invention , the aspiration takes place continuously by a peristaltic pump at a flow speed comprised between 10 and 16 ml / min and said extrusion takes place through the “ air monojet ” system using a fluid flow , preferably air , comprised between 3 and 7 l / min . in the process , the exact calibration of said air flow , a characterising element of the entire method , is ensured by the below components of the system that are not present in previous methods ( including that used in the “ closest prior art ”). before coming into contact with said suspension of said stage b ) said air flow is subject to the following operations with the following devices : the membrane pressure reducer swagelok ( kpr1jrf411a20000 ) which is capable of ensuring high reproducibility of the output pressure and so as to obtain a very low pressure drop in the flow / non flow transient below 0 . 3 bar , serves for stabilising and making the air flow to be sent to the extruder reproducible ; regulation through a micrometric valve swagelok ( ss - ss6mm ), in output to the pressure regulator , which allows regulating very finely the output air flow ( 0 - 10 nl / min ) with a high reproducibility in the flow / non flow transient and maintaining linearity between number of revolutions and dispensed flow ; with rotating float flow meter ( rotametro ) yokogawa , supplied by precision fluid ( ragk41 - toss - ssnnn - m741a - ttcgn * a ), located downstream of the micrometric valve , which allows a precise and quick reading of the output flow ( 0 - 10 nl / min ) and thus the adjustment thereof through the micrometric valve . a further object of the present invention are microcapsules containing sc obtainable according to the process of the invention , one of the features thereof is to exhibit the secretion of igf - 1 of microencapsulates sc identical to that of non - microencapsulates or “ free ” sc . a further object of the present invention is the use of sertoli cells , advantageously microencapsulated according to the process of the invention , as sole therapeutic agent for the production of a medicament of the prevention and radical cure of t1dm . according to the invention , the microcapsules obtained can be subject to washing operations and / or further coating with natural and / or artificial polymers . compared to the prior art , the process of the invention allow a ) producing microcapsules of smaller size , with fixed diameters ( starting from 300 μm ) and perfectly homogeneous , without the presence of “ tails ” structures and above all , without loss of vitality and functionality of the microencapsulated sc ; b ) increasing the number of microencapsulated sc by ml of alginate from 10 6 scs to 20 6 sc by ml of alginate with imaginable implications on the possibility of implanting a larger number of sc in the smallest possible volume of polymer and c ) increasing the functionality of microencapsulated sc , in particular relating to the production of igf - 1 , the secretion thereof changes from 50 ng / ml / 20 × 10 6 cells ) to 80 ng / ml / 20 × 10 6 cells substantially equal to that of “ free ” sc . with reference to the present invention , it should be noted that 1 . for the first time , microencapsulated sc are proposed as final therapeutic approach , inducing the neogenesis of patient &# 39 ; s beta - cell , destroyed by the autoimmune process . 2 . an optimisation of the microencapsulation process has been obtained which leads to the production of microcapsules with improved features , such as the reduction of mean dimensions , the reduced polydispersity and the absence of morphological deformities of the microcapsules (“ tails ” and coalescences ). a further object of the present invention are compositions comprising sc contained in microcapsules obtainable by the process of the invention together with physiologically tolerable carriers to use for the prevention and treatment of t1dm . an example of carrier consists of saline for intraperitoneal administration . the polymers usable for microencapsulating the sc are not available on the market in the highly purified form strictly necessary for applications requiring parenteral administrations , such as human transplants . in these cases , in fact , strict internationally recognised criteria of “ quality control ” are required ( see guidelines of the ministry of health and of u . s . pharmacopeia ). most commercial products , in fact , have quite high endotoxin levels ( generally comprised between 30 , 000 and 60 , 000 eu / g ) which make them totally unsuitable for transplant procedures , which require endotoxin levels not higher than 100 eu / g . as a consequence of the above , all the polymers used for producing microparticles are suitably subject to subsequent purification cycles that allow the drastic reduction of the endotoxins present . the sc may be isolated and purified from various animal sources , generally prepuberals . after anaesthesia , the animals are subject to bilateral orchiectomy . after the removal of the epididymis , the testicles are subject to multienzymatic digestion . once the digestion is complete , the tubular tissue is subject to filtration . the tubules thus obtained are placed in a culture at 37 ° c . in a 5 % atmosphere of co2 . after 48 hours in incubator , the sc start adhering to the culture plates , forming a cellular monolayer . the sc obtained are analysed in terms of purity , vitality and functionality . the cellular vitality test is routinely conducted immediately after the isolation , on the second day of culture and immediately before and after the microencapsulation process . the sc may be immobilised into microcapsules consisting of various hydrogels consisting of hydrophilic polymers used alone or in mixtures . the initial phase of the microencapsulation process envisages the obtainment of a continuous and calibrated flow of microdroplets . various procedures may be used for obtaining the microdroplets : ( a ) “ air - monojet ” microencapsulator , ( b ) automatic vibrating encapsulator , ( c ) electrostatic microencapsulator e ( d ) microfluidic lab - on - a - chip systems . once a flow of microdroplets with controlled and homogeneous dimensions is obtained , these are transformed into solid microspheres through gelification procedures . for example : converging monolayers of sc are treated to obtain a homogeneous cellular suspension , the sc are resuspended in the various ultrapure polymeric solutions ( obtained as described in section “ purification of polymers ”) and finally , the microcapsules obtained in the gelling bath are washed and isolated . the microcapsules produced may be used as such or be further coated with various natural , semi - synthetic or synthetic polymeric layers . the method proposed therefore allows ( as shown by the pictures of fig3 ) immobilising the sc into microcapsules with highly homogeneous dimensions , without morphological defects ( presence of coalescences or “ tail ” structures ), ensuring that the vitality and functionality features of the encapsulated cells are maintained . the microparticle biocompatibility is assessed through the intraperitoneal implant carried out through abdominal incision . the body weight of each recipient animal is monitored during all the in vivo study . at different times from the transplant , the microcapsules are explanted to assess their morphology and function of the encapsulated cells . the general features of the recovered microspheres were determined through microscopic analysis , assessing both the morphology and any presence of inflammatory cells of the capsule surface . the vitality of microencapsulated sc was also assessed using the dual colouring technique with eb / fda . it has been proved that the intraperitoneal transplant of microencapsulated sc in saline is capable of both preventing and treating t1dm in “ stringent ” animal models of human t1dm , such as nod rats . advantageously , but not exclusively , the administration of the product obtained from the microencapsulation of sc according to the invention takes place by intraperitoneal administration , with the product carried in saline . a further object of the invention is a device for producing microcapsules advantageously for applying the process of the invention . the device and the operation thereof shall now be described with reference to fig9 . a first container 2 cooperates with flow dispensing means 4 , advantageously a volumetric pump , for delivering suspension 1 through the catching tube 3 to a needle - type element 5 . the needle - type element 5 exhibits a buttonhole opening 6 in the lateral wall thereof and output hole 7 . a joint 8 allows a pressure fluid current 10 , preferably air , coming from a generator 9 and regulated by adjusting means 11 , to enter inside element 5 . by suitably regulating current 10 it is possible to interrupt the suspension flow and obtain microdroplets 13 of homogeneous size , which form gel in a solution containing divalent cations present in a second container 12 . the airjet instrument mentioned above and the conditions described are applied for obtaining the homogeneous microcapsules . development of a prototype of microencapsulator usable in sterility conditions and glp microencapsulation of sertoli cells into alginate - based microspheres and assessment of the in vivo biocompatibility and functionality sodium alginate obtained through a process of sequential filtrations , was used as base polymer for the production of microcapsules , usually available in a 1 - 6 % ( w / v ) solution , appropriately stored in a place protected from light and at a temperature of 4 °- 6 ° c . said compound is stable over time for about 5 years , has an endotoxin content not higher than 20 eu / g and a virtually absent protein content (& lt ; 0 . 4 %— another criterion of “ bioinvisibility ” of u . s . fda ). the sc were isolated from testicles of baby swine ( 7 - 15 days old ) “ large - white ”. after anaesthesia through the i . m . administration of 0 . 1 mg / kg azaperon ( stresnil ® 40 mg / ml , janssen , brusselle , belgium ) and 15 mg / kg ketamine ( imalgene ® 100 mg / ml , gellini farmaceutici , the swine were subject to bilateral orchiectomy . after the removal of the epididymis , the testicles are decorticated from the albuginea , finely chopped into small tissue fragments ( 1 - 3 mm3 ) and immediately subject to a first enzymatic digestion based on collagenase p ( roche diagnostics , s . p . a ., monza , italy ) ( 2 mg / ml ) in hbss ( sigma chemical co , st . louis , usa ). the digestion is continued up to the separation of the seminiferous tubules . the collected tubules are then washed in hbss and centrifuged at 500 r . p . m . after the wash , the tubules are incubated with a solution of hbss containing trypsin ( 2 mg / ml ) and dnase i ( sigma ). after the completion of the second digestion , the trypsin solution is diluted 1 : 1 with hank &# 39 ; s + 20 % fbs to stop the enzymatic activity thereof . after further washes with hbss , the tubules are separated from the peritubular cells through a light centrifugation at 300 rpm . the “ pellet ” containing the tubular tissue is suitably filtered with a stainless steel filter with a 500 μm mesh opening . finally , in order to remove any peritubular and leydig cells contaminating the preparation , the suspension containing the tubules is further centrifuged at 800 rpm for 5 min and the resulting pellet is treated for 7 min with a glycine 1 m solution and edta 2 mm in hbss at ph 7 . 2 . the tubules thus obtained are placed in a culture in ham f12 ( euroclone ) supplemented with retinoic acid 0 . 166 nm ( sigma ) and with 5 ml / 500 ml insulin - transferrin - selenium ( its ) ( becton dickinson # 354352 ), at 37 ° c . in a 5 % atmosphere of co2 . after 48 hours of culture , the sc start adhering to the culture plates , forming a cellular monolayer . in order to remove the residual germ cells ( which , as known , if implanted in the peritoneal cavity may give rise to dysgerminoms ), the sc monolayers are treated with a buffer , tris -( hydroxymethyl )- aminomethane hydrochloride ( tris ) ( sigma ) that allows eliminating the residual germ cells through osmotic lysis . finally , the sc are grown in the above conditions , usually in 75 cm2 flasks . the sc obtained were analysed in terms of purity , vitality and functionality . the purity of the sc , which was higher than 90 %, was assessed by immunocytochemistry techniques , incubating the preparation with anti - mullerian inhibiting factor ( mis ) and fluorescin anti - vimentin antibodies , which respectively mark the mis and vimentin molecules , both expressed by the sc only ( fig1 a , b ). to prove the reduced presence of leydig and peritubular cells as possible contaminants , the sc preparations were subject to histochemical assessments . these tests allow assessing both the presence of alkaline phosphatase ( colouring with fast - red ) typical of peritubular cell , and of the 3 - β - hydroxy - steroidodehydrogenase enzyme ( colouring with nitro - blue tetrazolium ) which on the other hand is typical of leydig cells ( fig1 c , d ). the results obtained with these histochemical assays have allowed to prove the presence of 5 - 8 % of peritubular and leydig cells ; these cellular populations , moreover , are useful ( when present in these proportions ) to ensure a molecular “ cross - talk ” favourable for the correct functionality of these populations of testicular cells . the vitality of sc was determined by treatment with ethidium bromide ( eb ) and fluorescein - diacetate ( fda ) ( sigma ). the cells , observed by a fluorescence microscope , in all conditions showed a vitality higher than 95 %. the cellular vitality test is routinely conducted immediately after the isolation , on the second day of culture and immediately before the microencapsulation process . the sc were immobilised into microcapsules consisting of various polysaccharide polymers used alone or in mixtures . the selected polymer was sodium alginate ultrapurified at our laboratories . the initial phase of the microencapsulation process envisages the obtainment of a continuous and calibrated flow of microdroplets starting from cellular suspension of sc in an aqueous polysaccharide suspension with a polymeric concentration variable between 1 and 5 % ( w / v ). various procedures were and may be used for obtaining the microdroplets : ( a ) “ air - monojet ” microencapsulator , ( b ) automatic vibrating encapsulator , ( c ) electrostatic microencapsulator e ( d ) microfluidic lab - on - a - chip systems . in particular , the method selected ( a ), based on a semi - automatic , compact , sterilisable and transportable microencapsulator ( fig2 , a shows an overall view of the system ), has allowed producing microcapsules containing sc with highly homogeneous dimensions ( 300 to 700 μm diameter ), without any evident morphological flaw ( such as the presence of coalescences or “ tail ” structures ) and above all , without the loss of vitality and functionality of the microencapsulated sc . panel b of fig2 schematises the procedure of the microencapsulation process through “ air - monojet ”. once a flow of microdroplets with controlled and homogeneous dimensions is obtained , these are transformed into solid microspheres through a gelification procedure which envisages the forming of ionic links with divalent ions according to a method developed and validated at our laboratories . in particular , converging monolayers of sc are treated with 0 . 05 % trypsin / edta ( gibco , grandisland , usa ) ( 2 min ), in order to obtain a homogeneous cellular suspension . once washed , the sc are counted by hemocytometric analysis and tested for vitality . afterwards , the sc are resuspended in the various ultrapure polymeric suspensions in concentrations variable between 1 . 5 - 2 % ( w / v ) of ag . for the production of microcapsules with the “ air - monojet ” system , the sc suspension in the polymers is continuously aspired by a peristaltic pump at a flow speed comprised between 10 and 16 ml / min . the cellular suspension is then extruded through the “ air monojet ” system ( using an air flow comprised between 3 and 7 l / min ). during the entire process , the sc suspension is kept under light stirring to prevent the cellular aggregation and the possible formation of microcapsules with non - homogeneous distribution of sc therein . the microdroplets produced are gellied with a solution containing divalent cations , such as ca + 2 or ba + 2 ( 0 . 5 - 2 . 5 %, w / v ). in this way , the microdroplets are instantly transformed into gel microspheres . afterwards , the microcapsules are left to settle for periods variable between 2 and 15 min into the gelling bath . at the end of this step , the microcapsules are subject to repeated washing cycles with saline . the microcapsules produced may be used as such or be further coated through sequential incubation in solutions containing natural , semi - synthetic or synthetic cationic polymers . for example , poly - l - ornithine ( plo ) was used at 0 . 12 % ( for 10 min ) and at 0 . 06 % ( for 6 min ). finally , the microcapsules coated with plo are further treated with a diluted solution of polysaccharide , to provide the highly biocompatible final outer coating . fig3 shows the microphotographs of alginate - based microcapsules obtained by the procedure described above , both using only barium ions ( a - c ) and the procedure of the multiple coating with calcium / polyornithine / polymer ions ( b - d ). the method proposed therefore allows ( as shown by the pictures of fig3 ) immobilising the sc into microcapsules with highly homogeneous dimensions , without morphological defects , such as the presence of coalescences or “ tail ” structures , and finally , ensuring that the vitality and functionality features of the encapsulated cells are maintained . after general anaesthesia , induced by intra - peritoneal administration of 100 mg / kg ketamine ( parke - davis / pfizer , karlsruhe , germany ) and 15 mg / kg xylazine ( bayer , leverkusen , germany ), the alginate microparticles were introduced through a small abdominal incision in the peritoneal cavity of female nod rats ( harlan , italy , approximate weight of 25 g ). 106 microencapsulated sc were implanted in each animal . the body weight of each recipient rat was monitored during all the in vivo study . after 4 months from the transplant , the microcapsules were explanted , after anaesthesia , from the peritoneal cavity of the animals to assess their morphology and function of the contents . the microcapsules were recovered by peritoneal wash using saline . the general features of the recovered microspheres were determined through microscopic analysis , assessing both the morphology and any presence of inflammatory cells of the capsule surface . the vitality of microencapsulated sc was also assessed using the dual colouring technique with eb / fda . the microphotographs shown in fig4 ( a - b ) show that the polysaccharidic microparticles keep high biocompatibility standards , as shown by the minimum levels of inflammatory cells present on the capsular surface . moreover , the microencapsulated sc both in barium ( fig4 a ) and calcium ( fig4 b ) alginate , keep excellent vitality levels 4 months after the implantation ( fig4 c ). e ) assessment of the in vivo and in vitro activity of microencapsulated sc the present invention finds application in the field of transplantation biotechnologies , such as for example the prevention and treatment of t1dm . actually , at our laboratories we have proved that the intraperitoneal transplant of microencapsulated sc in barium alginate microspheres ( 206 / rat ) is capable of both preventing and treating t1dm in “ stringent ” animal models of human t1dm , such as nod rats . in particular , sc microencapsulated into barium alginate ( baag ) microspheres were transplanted , after 72 hours culture , in the peritoneal cavity of pre - diabetic nod rats and affected by evident diabetes . the implantation was carried out in a general anaesthesia through laparotomy . the transplanted animals were then monitored with weekly checks for their body weight and glycaemia before and after meals . the experimental protocol we followed envisaged groups of animals subject to different treatments as indicated below . group c : “ naive ” pre - diabetic animals treated with intraperitoneal implant of microencapsulated sc . group d : “ naive ” pre - diabetic animals treated with intraperitoneal implant of “ free ” sc : ( 206 / rat ). group e : animals with spontaneous diabetes treated with intraperitoneal implant of microencapsulated sc . during the course of the in vivo study , some animals were sacrificed to assess the peripheral immunological layout through collection of spleen , peripancreatic lymph nodes and pancreas with concurrent histomorphological and immunocytochemical examinations . the complete analysis of in vivo experiments on nod rats has allowed proving that microencapsulated sc transplanted in pre - diabetic animals suffering from spontaneous diabetes allowed obtaining , important therapeutic results , as shown below . ( a ) microencapsulated sc are capable of preventing the onset of t1dm in nod rats . this sensational result can be obtained from the analysis of the percentages of spontaneous onset of t1dm . in fact , this pathology occurred spontaneously in 85 % of the animals in group a ( fig5 b ). this result is perfectly in line with the percentages of occurrence of t1dm declared by the supplier of nod rats ( taconic ) ( fig5 a ). on the other hand , in the animals of group c ( the pre - diabetic ones treated with encapsulated sc ), the percentage of onset of t1dm was only 9 % ( fig5 c ). finally , in the animals of group d ( pre - diabetic treated with intraperitoneal implant of “ free ” sc ), the percentage of onset of t1dm was greatly reduced compared to that of the “ naive ” ( 19 %), although higher than in the animals of group c ( fig5 d ). ( b ) the microencapsulated sc are capable of normalising , in just 7 - 15 days from the implant , the glycaemic values ( with the attainment of glycaemia below 200 mg / dl ) in more than 60 % of rats in group e ( n = 30 ) that had spontaneously developed diabetes ( fig6 a ). on the other hand , the animals in group b ( diabetics treated with empty capsules ) always kept high levels of glycaemia , dying quickly , in 1 - 2 weeks . finally , the animals in group f ( n = 30 ) ( diabetics treated with intraperitoneal implant of “ free ” sc ) were able to normalise the glycaemic values although in a lower percentage , equal to about 40 %. ( c ) studies carried out on lymph nodes , pancreas and spleens have shown that the sc are capable of “ re - educating ” the immune system of the animals in groups c and e , “ blocking ” the autoimmune attack responsible for the disease , as can be seen from fig7 relating to real time polymerase chain reaction ( pcr ) results on the splenocytes of treated animals . in particular , such results show that one of the main effects of the treatment with sc is their capacity to induce in vivo foxp3 + cells . foxp3 is a selective marker of t cells with regulating features , that is , capable of regulating the activation and the proliferation of several cells involved in immune responses and the number whereof is reduced in the nod rat model . ( d ) histochemical assays carried out on all the groups of animals studied show that the treatment with sc is capable of removing the insulitic mononuclear infiltrate at the pancreas level in animals of groups c and e compared to those of the control groups ( a and b ) ( fig8 ). moreover , such effect was followed by the activation of pancreatic mesenchymal stem cells capable of generating new β - cells which are capable of normalising glycaemia in animals treated with sc , as they are not undermined by the autoimmune attack anymore . the remodulation of the immune response after treatment with sc is mediated by the activation of the immunoregulatory pathway of the indoleamine 2 3 - dioxygenase ( ido ) enzyme , an isoform whereof is expressed and functioning in sc , too . 1 . decesaris p , filippini a , cervelli c , riccioloi , a . ; muci , s . ; starace , g . ; stefanini , m . ; ziparo , e . immuno - suppressive molecules produced by sertoli cells cultured in vitro : biological effects on lymphocytes . biochem . biophys res . commun . 1992 , 186 : 1639 - 1646 . 2 . lynch d h , ramsdell f , alderson m r . fas and fasl in the homeostatic regulation of immune responses . immunol . today 1995 , 16 : 569 - 574 . 3 . suarez - pinzon w , korbutt g s , power r , hooten j , rajotte r v , rabinovitch a . testicular sertoli cells protect islet b - cells from autoimmune destruction by a transforming growth factor - βl - dependent mechanism . diabetes 2000 , 49 : 1810 - 1818 . 4 . emerich , d . f ., hemendinger , r ., and halberstadt , c . r . the testicular - derived sertoli cell : cellular immunoscience to enable transplantation . cell transplantation 12 , 335 , 2003 . 5 . luca , g ., calvitti , m ., nastruzzi , c ., bilancetti , l ., becchetti , e ., mancuso , f ., calafiore r . encapsulation , in vitro characterization and in vivo biocompatibility of sertoli &# 39 ; s cells in alginate based microcapsules . tissue eng . 2007 , 13 : 641 - 648 .
an apparatus for production of microcapsules includes a volumetric pump configured to deliver a polysaccaridic suspension through a catching tube . a needle - type element is configured to receive the suspension through the catching tube , and the needle - type element has a button hole opening in a lateral wall thereof and an output hole that outputs the suspension . the button hole opening receives a pressure fluid current . a pressure regulator is coupled to the button hole opening to regulate the pressure fluid current to interrupt a suspension flow and obtain microdroplets of homogeneous size exiting the output hole . the microdroplets are received in a receiving container in a solution including divalent cations or polycationic substances to form a gel such that homogeneous microcapsules are formed .