Release characteristics of cellulose sulphate capsules and production of cytokines from encapsulated cells

Advancements in Oral Delivery Systems for Probiotics Based on Polysaccharides

Probiotics are an essential dietary supplement for intestinal flora balance, inhibition of pathogenic bacteria and immune regulation. However, probiotic inactivation during gastrointestinal transportation remains a big challenge for oral administration. Hence, oral delivery systems (ODSs) based on polysaccharides have been constructed to protect probiotics from harsh environments. Cellulose, chitosan, alginate and their derivates have been used to form a protective layer for probiotics. This review summarizes the superiority and application of polysaccharides in forming protective layers for probiotics. Meanwhile, ODS processes including extrusion, emulsion and spray drying are also summarized. The preparation technique mechanism, the microparticle formation process and especially the role polysaccharides serve in the preparation process are overviewed. Lastly, the need for cell viability retention during the dehydration and construction of core-shell ODS microparticles is emphasized in this review.

Naturally and Chemically Sulfated Polysaccharides in Drug Delivery Systems

Sulfated polysaccharides have always attracted much attention in food, cosmetic and pharmaceutical industries. These polysaccharides can be obtained from natural sources such as seaweeds (agarans, carrageenans, fucoidans, mannans and ulvans), or animal tissues (glucosaminoglycans). In the last few years, several neutral or cationic polysaccharides have been sulfated by chemical methods and anionic or amphoteric derivatives were obtained, respectively, for drug delivery and other biomedical applications. An important characteristic of sulfated polysaccharides in this field is that they can associate with cationic drugs generating polyelectrolyte-drug complexes, or with cationic polymers to form interpolyelectrolyte complexes, with hydrogel properties that expand even more their applications. The aims of this chapter are to present the structural characteristics of these polysaccharides, to describe the methods of sulfation applied and to review extensively and discuss developments in their use or their role in interpolyelectrolyte complexes in drug delivery platforms. A variety of pharmaceutical dosage forms which were developed and administered by multiple routes (oral, transdermal, ophthalmic, and pulmonary, among others) to treat diverse pathologies were considered. Different IPECs were formed employing these sulfated polysaccharides as the anionic component. The most widely investigated is κ-carrageenan. Chitosan is usually employed as a cationic polyelectrolyte, with a variety of sulfated polysaccharides, besides the applications of chemically sulfated chitosan. Although chemical sulfation is often carried out in neutral polysaccharides and, to a less extent, in cationic ones, examples of oversulfation of naturally sulfated fucoidan have been found which improve its drug binding capacity and biological properties.

Stem Cell's Secretome Delivery Systems

Stem cells' secretome contains biomolecules that are ready to give therapeutic activities. However, the biomolecules should not be administered directly because of their in vivo instability. They can be degraded by enzymes or seep into other tissues. There have been some advancements in localized and stabilized secretome delivery systems, which have increased their effectiveness. Fibrous, in situ, or viscoelastic hydrogel, sponge-scaffold, bead powder/ suspension, and bio-mimetic coating can maintain secretome retention in the target tissue and prolong the therapy by sustained release. Porosity, young's modulus, surface charge, interfacial interaction, particle size, adhesiveness, water absorption ability, in situ gel/film, and viscoelasticity of the preparation significantly affect the quality, quantity, and efficacy of the secretome. Therefore, the dosage forms, base materials, and characteristics of each system need to be examined to develop a more optimal secretome delivery system. This article discusses the clinical obstacles and potential solutions for secretome delivery, characterization of delivery systems, and devices used or potentially used in secretome delivery for therapeutic applications. This article concludes that secretome delivery for various organ therapies necessitates the use of different delivery systems and bases. Coating, muco-, and cell-adhesive systems are required for systemic delivery and to prevent metabolism. The lyophilized form is required for inhalational delivery, and the lipophilic system can deliver secretomes across the blood-brain barrier. Nano-sized encapsulation and surface-modified systems can deliver secretome to the liver and kidney. These dosage forms can be administered using devices such as a sprayer, eye drop, inhaler, syringe, and implant to improve their efficacy through dosing, direct delivery to target tissues, preserving stability and sterility, and reducing the immune response.

Recent Progress on Cellulose-Based Ionic Compounds for Biomaterials

Glycans play important roles in all major kingdoms of organisms, such as archea, bacteria, fungi, plants, and animals. Cellulose, the most abundant polysaccharide on the Earth, plays a predominant role for mechanical stability in plants, and finds a plethora of applications by humans. Beyond traditional use, biomedical application of cellulose becomes feasible with advances of soluble cellulose derivatives with diverse functional moieties along the backbone and modified nanocellulose with versatile functional groups on the surface due to the native features of cellulose as both cellulose chains and supramolecular ordered domains as extractable nanocellulose. With the focus on ionic cellulose-based compounds involving both these groups primarily for biomedical applications, a brief introduction about glycoscience and especially native biologically active glycosaminoglycans with specific biomedical application areas on humans is given, which inspires further development of bioactive compounds from glycans. Then, both polymeric cellulose derivatives and nanocellulose-based compounds synthesized as versatile biomaterials for a large variety of biomedical applications, such as for wound dressings, controlled release, encapsulation of cells and enzymes, and tissue engineering, are separately described, regarding the diverse routes of synthesis and the established and suggested applications for these highly interesting materials.

Efficient protection of microorganisms for delivery to the intestinal tract by cellulose sulphate encapsulation

BACKGROUND

Gut microbiota in humans and animals play an important role in health, aiding in digestion, regulation of the immune system and protection against pathogens. Changes or imbalances in the gut microbiota (dysbiosis) have been linked to a variety of local and systemic diseases, and there is growing evidence that restoring the balance of the microbiota by delivery of probiotic microorganisms can improve health. However, orally delivered probiotic microorganisms must survive transit through lethal highly acid conditions of the stomach and bile salts in the small intestine. Current methods to protect probiotic microorganisms are still not effective enough.

RESULTS

We have developed a cell encapsulation technology based on the natural polymer, cellulose sulphate (CS), that protects members of the microbiota from stomach acid and bile. Here we show that six commonly used probiotic strains (5 bacteria and 1 yeast) can be encapsulated within CS microspheres. These encapsulated strains survive low pH in vitro for at least 4 h without appreciable loss in viability as compared to their respective non-encapsulated counterparts. They also survive subsequent exposure to bile. The CS microspheres can be digested by cellulase at concentrations found in the human intestine, indicating one mechanism of release. Studies in mice that were fed CS encapsulated autofluorescing, commensal E. coli demonstrated release and colonization of the intestinal tract.

CONCLUSION

Taken together, the data suggests that CS microencapsulation can protect bacteria and yeasts from viability losses due to stomach acid, allowing the use of lower oral doses of probiotics and microbiota, whilst ensuring good intestinal delivery and release.

Cell microencapsulation technologies for sustained drug delivery: Clinical trials and companies

In recent years, cell microencapsulation technology has advanced, mainly driven by recent developments in the use of stem cells or the optimization of biomaterials. Old challenges have been addressed from new perspectives, and systems developed and improved for decades are now being transferred to the market by novel start-ups and consolidated companies. These products are mainly intended for the treatment of diabetes mellitus (DM), but also cancer, central nervous system (CNS) disorders or lysosomal diseases, among others. In this review, we analyze the results obtained in clinical trials to date and define the global key players that will lead the cell microencapsulation market to bring this technology to the clinic in the future.

Recent advances in composites based on cellulose derivatives for biomedical applications

Cellulose derivatives represent a viable alternative to pure cellulose due to their solubility in water and common organic solvents. This, coupled with their low cost, biocompatibility, and biodegradability, makes them an attractive choice for applications related to the biomedicine and bioanalysis area. Cellulose derivatives-based composites with improved properties were researched as films and membranes for osseointegration, hemodialysis and biosensors, smart textile fibers, tissue engineering scaffolds, hydrogels and nanoparticles for drug delivery. The different preparation strategies of these polymeric composites as well as the most recent available experimental results were described in this review. General aspects such as structure and properties of cellulose extracted from plants or bacterial sources, types of cellulose derivatives and their synthesis methods were also discussed. Finally, the future perspectives related to composites based on cellulose derivatives were highlighted and some conclusions regarding the reviewed applications were drawn.

Semipermeable Cellulose Beads Allow Selective and Continuous Release of Small Extracellular Vesicles (sEV) From Encapsulated Cells

The clinical benefit of therapies using Mesenchymal Stem Cells (MSCs) is attributable to their pleiotropic effect over cells and tissues, mainly through their secretome. This paracrine effect is mediated by secreted growth factors and extracellular vesicles (EV) including small EV (sEV). sEV are extra-cellular, membrane encompassed vesicles of 40 to 200 nm diameter that can trigger and signal many cellular responses depending on their cargo protein and nucleic acid repertoire. sEV are purified from cell culture conditioned media using several kits and protocols available that can be tedious and time-consuming, involving sequences of ultracentrifugations and density gradient separations, making their production a major challenge under Good Manufacturing Practices (GMP) conditions. We have developed a method to efficiently enrich cell culture media with high concentrations of sEV by encapsulating cells in semipermeable cellulose beads that allows selectively the release of small particles while offering a 3D culture condition. This method is based on the pore size of the capsules, allowing the release of particles of ≤ 200 nm including sEV. As a proof-of-principle, MSCs were encapsulated and their sEV release rate (sEV-Cap) was monitored throughout the culture and compared to sEV isolated from 2D seeded cells (sEV-2D) by repetitive ultracentrifugation cycles or a commercial kit. The isolated sEV expressed CD63, CD9, and CD81 as confirmed by flow cytometry analysis. Under transmission electron microscopy (TEM), they displayed the similar rounded morphology as sEV-2D. Their corresponding diameter size was validated by nanoparticle tracking analysis (NTA). Interestingly, sEV-Cap retained the expected biological activities of MSCs, including a pro-angiogenic effect over endothelial cells, neuritic outgrowth stimulation in hippocampal neurons and immunosuppression of T cells in vitro. Here, we successfully present a novel, cost, and time-saving method to generate sEV from encapsulated MSCs. Future applications include using encapsulated cells as a retrievable delivery device that can interact with the host niche by releasing active agents in vivo, including sEV, growth factors, hormones, and small molecules, while avoiding cell clearance, and the negative side-effect of releasing undesired components including apoptotic bodies. Finally, particles produced following the encapsulation protocol display beneficial features for their use as drug-loaded delivery vehicles.