Polyphenols-Loaded Sericin Self-Assembling Nanoparticles: A Slow-Release for Regeneration by Tissue-Resident Mesenchymal Stem/Stromal Cells

Therapeutic potential of silkworm sericin in wound healing applications

Chronic wounds are characterised by an imbalance between pro and anti-inflammatory signals, which result in permanent inflammation and delayed re-epithelialization, consequently hindering wound healing. They are associated with bacterial infections, tissue hypoxia, local ischemia, reduced vascularization, and MMP-9 upregulation. The global prevalence of chronic wounds has been estimated at 40 million in the adult population, with an alarming annual growth rate of 6.6%, making it an increasingly significant clinical problem. Sericin is a natural hydrophilic protein obtained from the silkworm cocoon. Due to its biocompatibility, biodegradability, non-immunogenicity, and oxidation resistance, coupled with its excellent affinity for target biomolecules, it holds great potential in wound healing applications. The silk industry discards 50,000 tonnes of sericin annually, making it a readily available material. Sericin increases cell union sites and promotes cell proliferation in fibroblasts and keratinocytes, thanks to its cytoprotective and mitogenic effects. Additionally, it stimulates macrophages to release more therapeutic cytokines, thus improving vascularization. This review focuses on the biological properties of sericin that contribute towards enhanced wound healing process and its mechanism of interaction with important biological targets involved in wound healing. Emphasis is placed on diverse wound dressing products that are sericin based and the utilisation of nanotechnology to design sericin nanoparticles that aid in chronic wound management.

Preparation, characterization and drug release properties of pH sensitive Zingiber officinale polysaccharide hydrogel beads

The aim of this study was to prepare a drug carrier that could deliver oral insulin to the intestine. A hydrogel beads composed of sodium carboxymethyl cellulose (CMC), Zingiber offtcinale polysaccharide (ZOP) and chitosan (CS) were prepared by ionic gel method as insulin carrier. Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), Scanning electron microscopy (SEM) and thermogravimetric (TGA) showed that the hydrogel was formed by metal ion coordination between ZOP and CMC and Fe3+, and CS was coated on the surface of the hydrogel ball in the form of non covalent bond. The results showed that the swelling process of hydrogel spheres has significant pH sensitivity. In addition, the hydrogel beads successfully coated insulin, and the drug loading rate (DL) of (ZOP/CMC-Fe3+)@CS could reach 69.43 ± 7.32 mg/g, and the entrapment efficiency (EE) could reach 66.94 ± 7.43 %. In vitro release experiments, the release rate of (CMC/ZOP-Fe3+)@CS in simulated gastric fluid (SGF) for 2 h was <20 %, and the cumulative release rate of insulin after 9 h in simulated intestinal fluid (SIF) reached over 90 %. The results showed that the hydrogel beads prepared in this work could be used as a potential carrier for delivering oral insulin.

A pH-sensitive hydrogel based on carboxymethylated konjac glucomannan crosslinked by sodium trimetaphosphate: Synthesis, characterization, swelling behavior and controlled drug release

The pH-sensitive hydrogel consisting of carboxymethylated konjac glucomannan (CMKGM) and sodium trimetaphosphate (STMP) was prepared for a potential intestinal targeted delivery system. Both the CMKGM and the CMKGM hydrogel were characterized by FT-IR spectra, X-ray diffraction (XRD), and thermogravimetric analysis (TGA). The Congo red and atomic force microscope (AFM) results showed a coil-to-helix transition of CMKGM in alkaline conditions with the degree of substitution (DS) increased from 0.20 to 0.49. Rheological measurements indicated that the DS and the STMP content collectively influence the mechanical stiffness and swelling properties of the obtained hydrogels. In addition, the swelling behavior of the hydrogels revealed that they were sensitive to pH value changes and were following a Korsmeyer-Peppas gastrointestinal release behavior, indicating that the release was controlled by non-Fickian diffusion. Furthermore, all the results suggested that the prepared pH-sensitive hydrogel may serve as a potential biomaterial for the intestine-targeted delivery system.

Sericin/crocetin micro/nanoparticles for nucleus pulposus cells regeneration: An “active” drug delivery system

Introduction: Initiation and progression of intervertebral disk degeneration are linked to oxidative stress, with reactive oxygen species being a key factor. Therefore, as a potentially novel approach able to regenerate the damaged intervertebral disk, this work aimed to prepare an “active per sé” drug delivery system by combining sericin and crocetin: both are bioactive compounds with antioxidant, anti-inflammatory, immunomodulant and regenerative properties.

Methods: In detail, sericin nanoparticles were prepared using crocetin as a cross-linker; then, the nanoparticle dispersions were dried by spray drying as it is (NP), with an excess of sericin (NPS) or crocin/crocetin (NPMix), obtaining three microparticle formulations.

Results and Discussion: Before drying, the nanoparticles were nanometric (about 250 nm), with a negative surface charge, and appeared spherical and smooth. Following the drying process, spherical and smooth microparticles were obtained, with a mean diameter of about 1.7–2.30 μm. NPMix was the most active in antioxidant and anti-tyrosinase activities, likely due to the excess of crocin/crocetin, while NPS had the best anti-elastase activity, likely due to sericin in excess. Furthermore, all the formulations could prevent oxidative stress damage on nucleus pulposus cells, with NPMix being the best. Overall, the intrinsic anti-tyrosinase and anti-elastase activities and the ability to protect from oxidative stress-induced damages justify future investigations of these “active per sé” formulations in treating or preventing intervertebral disk degeneration.

Silk sericin as building blocks of bioactive materials for advanced therapeutics

Silk sericin is a class of protein biopolymers produced by silkworms. Increasing attention has been paid to silk sericin for biomedical applications in the last decade, not only because of its excellent biocompatibility and biodegradability but also due to the pharmacological activities stemming from its unique amino acid compositions. In this review, the biological properties of silk sericin, including curing specific diseases and promoting tissue regeneration, as well as underlying mechanisms are summarized. We consider the antioxidant activity of silk sericin as a fundamental property, which could account for partial biological activities, despite the exact mechanisms of silk sericin's effect remaining unknown. Based on the reactive groups on silk sericin, approaches of bottom-up fabrication of silk sericin-based biomaterials are highlighted, including non-covalent interactions and chemical reactions (reduction, crosslinking, bioconjugation, and polymerization). We then briefly present the cutting-edge advances of silk sericin-based biomaterials applied in tissue engineering and drug delivery. The challenges of silk sericin-based biomaterials are proposed. With more bioactivities and underlying mechanisms of silk sericin uncovered, it is going to boost the therapeutic potential of silk sericin-based biomaterials.

Progress in silk and silk fiber-inspired polymeric nanomaterials for drug delivery

The fields of drug and gene delivery have been revolutionized by the discovery and characterization of polymer-based materials. Polymeric nanomaterials have emerged as a strategy for targeted delivery because of features such as their impressive biocompatibility and improved availability. Use of naturally derived polymers in these nanomaterials is advantageous due to their biodegradability and bioresorption. Natural biopolymer-based particles composed of silk fibroins and other silk fiber-inspired proteins have been the focus of research in drug delivery systems due to their simple synthesis, tunable characteristics, and ability to respond to stimuli. Several silk and silk-inspired polymers contain a high proportion of reactive side groups, allowing for functionalization and addition of targeting moieties. In this review, we discuss the main classes of silk and silk-inspired polymers that are being used in the creation of nanomaterials. We also focus on the fabrication techniques used in generating a tunable design space of silk-based polymeric nanomaterials and detail how that translates into use for drug delivery to several distinct microenvironments.

Hybrid Nanoparticles of Proanthocyanidins from Uncaria tomentosa Leaves: QTOF-ESI MS Characterization, Antioxidant Activity and Immune Cellular Response

Previous studies in Uncaria tomentosa have shown promising results concerning the characterization of polyphenols with leaves yielding more diverse proanthocyanidins and higher bioactivities values. However, the polyphenols-microbiota interaction at the colonic level and their catabolites avoid the beneficial effects that can be exerted by this medicinal plant when consumed. In this regard, a new generation of hybrid nanoparticles has demonstrated improvements in natural compounds’ activity by increasing their bioavailability. In this line, we report a detailed study of the characterization of a proanthocyanidin-enriched extract (PA-E) from U. tomentosa leaves from Costa Rica using UPLC-QTOF-ESI MS. Moreover, two types of hybrid nanoparticles, a polymeric-lipid (F-1) and a protein-lipid (F-2) loaded with PA-E were synthesized and their characterization was conducted by dynamic light scattering (DLS), attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FT-IR), high-resolution transmission electron microscopy (HR-TEM), and encapsulation efficiency (%EE). In addition, in vitro release, antioxidant activity through 2,2-diphenyl-1-picrylhidrazyl (DPPH) as well as in vivo delayed-type hypersensitivity (DTH) reaction was evaluated. Results allowed the identification of 50 different compounds. The PA-E loaded nanoparticles F-1 and F-2 achieved encapsulation efficiency of ≥92%. The formulations exhibited porosity and spherical shapes with a size average of 26.1 ± 0.8 and 11.8 ± 3.3 nm for F-1 and F-2, respectively. PA-E increased its release rate from the nanoparticles compared to the free extract in water and antioxidant activity in an aqueous solution. In vivo, the delayed-type hypersensitive test shows the higher immune stimulation of the flavan-3-ols with higher molecular weight from U. tomentosa when administered as a nanoformulation, resulting in augmented antigen-specific responses. The present work constitutes to our knowledge, the first report on these bioactivities for proanthocyanidins from Uncaria tomentosa leaves when administrated by nanosystems, hence, enhancing the cellular response in mice, confirming their role in immune modulation.

Facile synthesis of pH-responsive sodium alginate/carboxymethyl chitosan hydrogel beads promoted by hydrogen bond

In this work, a novel synthesis strategy of sodium alginate/carboxymethyl chitosan hydrogel beads promoted by hydrogen bond was described. The beads were prepared by dropping the blends of two polymers into the citric acid solution. Besides hydrogen bonding, electrostatic interactions were also involved in the formation of the hydrogel beads. The thermal stability experiments revealed that the more the content of carboxymethyl chitosan, the better the thermal stability of the beads. The beads exhibited excellent pH sensitivity, pH reversibility, and lactoferrin loading capacity. The swelling ratio of the bead and its protein releasing profile was pH-dependent, which could prevent premature protein release in the gastric environment. Also, the circular dichroism results demonstrated that lactoferrin could maintain its structure during the loading and releasing process. The obtained results revealed that the hydrogel beads prepared in this work could be used as a potential protein carrier for oral delivery.

Biomaterials for Soft Tissue Repair and Regeneration: A Focus on Italian Research in the Field

Tissue repair and regeneration is an interdisciplinary field focusing on developing bioactive substitutes aimed at restoring pristine functions of damaged, diseased tissues. Biomaterials, intended as those materials compatible with living tissues after in vivo administration, play a pivotal role in this area and they have been successfully studied and developed for several years. Namely, the researches focus on improving bio-inert biomaterials that well integrate in living tissues with no or minimal tissue response, or bioactive materials that influence biological response, stimulating new tissue re-growth. This review aims to gather and introduce, in the context of Italian scientific community, cutting-edge advancements in biomaterial science applied to tissue repair and regeneration. After introducing tissue repair and regeneration, the review focuses on biodegradable and biocompatible biomaterials such as collagen, polysaccharides, silk proteins, polyesters and their derivatives, characterized by the most promising outputs in biomedical science. Attention is pointed out also to those biomaterials exerting peculiar activities, e.g., antibacterial. The regulatory frame applied to pre-clinical and early clinical studies is also outlined by distinguishing between Advanced Therapy Medicinal Products and Medical Devices.

In Vitro Interaction of Doxorubicin-Loaded Silk Sericin Nanocarriers with MCF-7 Breast Cancer Cells Leads to DNA Damage

In this paper, Bombyx mori silk sericin nanocarriers with a very low size range were obtained by nanoprecipitation. Sericin nanoparticles were loaded with doxorubicin, and they were considered a promising tool for breast cancer therapy. The chemistry, structure, morphology, and size distribution of nanocarriers were investigated by Fourier transformed infrared spectroscopy (FTIR–ATR), scanning electron microscopy (SEM) and transmission electron microscopy (TEM), and dynamic light scattering (DLS). Morphological investigation and DLS showed the formation of sericin nanoparticles in the 25–40 nm range. FTIR chemical characterization showed specific interactions of protein–doxorubicin–enzymes with a high influence on the drug delivery process and release behavior. The biological investigation via breast cancer cell line revealed a high activity of nanocarriers in cancer cells by inducing significant DNA damage.

Equine Mesenchymal Stem/Stromal Cells Freeze-Dried Secretome (Lyosecretome) for the Treatment of Musculoskeletal Diseases: Production Process Validation and Batch Release Test for Clinical Use

In the last decades, it has been demonstrated that the regenerative therapeutic efficacy of mesenchymal stromal cells is primarily due to the secretion of soluble factors and extracellular vesicles, collectively known as secretome. In this context, our work described the preparation and characterization of a freeze-dried secretome (Lyosecretome) from adipose tissue-derived mesenchymal stromal cells for the therapy of equine musculoskeletal disorder. An intraarticular injectable pharmaceutical powder has been formulated, and the technological process has been validated in an authorized facility for veterinary clinical-use medicinal production. Critical parameters for quality control and batch release have been identified regarding (i) physicochemical properties; (ii) extracellular vesicle morphology, size distribution, and surface biomarker; (iii) protein and lipid content; (iv) requirements for injectable pharmaceutical dosage forms such as sterility, bacterial endotoxin, and Mycoplasma; and (v) in vitro potency tests, as anti-elastase activity and proliferative activity on musculoskeletal cell lines (tenocytes and chondrocytes) and mesenchymal stromal cells. Finally, proteins putatively responsible for the biological effects have been identified by Lyosecretome proteomic investigation: IL10RA, MXRA5, RARRES2, and ANXA1 modulate the inflammatory process RARRES2, NOD1, SERPINE1, and SERPINB9 with antibacterial activity. The work provides a proof-of-concept for the manufacturing of clinical-grade equine freeze-dried secretome, and prototypes are now available for safety and efficacy clinical trials in the treatment of equine musculoskeletal diseases

Crocetin as New Cross-Linker for Bioactive Sericin Nanoparticles

The nose-to-brain delivery route is used to bypass the blood–brain barrier and deliver drugs directly into the brain. Over the years, significant signs of progress have been made in developing nano-drug delivery systems to address the very low drug transfer levels seen with conventional formulations (e.g., nasal solutions). In this paper, sericin nanoparticles were prepared using crocetin as a new bioactive natural cross-linker (NPc) and compared to sericin nanoparticles prepared with glutaraldehyde (NPg). The mean diameter of NPc and NPg was about 248 and 225 nm, respectively, and suitable for nose-to-brain delivery. The morphological investigation revealed that NPc are spherical-like particles with a smooth surface, whereas NPg seem small and rough. NPc remained stable at 4 °C for 28 days, and when freeze-dried with 0.1% w/v of trehalose, the aggregation was prevented. The use of crocetin as a natural cross-linker significantly improved the in vitro ROS-scavenging ability of NPc with respect to NPg. Both formulations were cytocompatible at all the concentrations tested on human fibroblasts and Caco-2 cells and protected them against oxidative stress damage. In detail, for NPc, the concentration of 400 µg/mL resulted in the most promising to maintain the cell metabolic activity of fibroblasts higher than 90%. Overall, the results reported in this paper support the employment of NPc as a nose-to-brain drug delivery system, as the brain targeting of antioxidants is a potential tool for the therapy of neurological diseases.

Impairment of Tissue-Resident Mesenchymal Stem Cells in Chronic Ulcerative Colitis and Crohn's Disease

BACKGROUND AND AIMS

Little is known about the presence and function of tissue-resident mesenchymal stem cells [MtSCs] within the gastrointestinal mucosa in health and inflammatory bowel disease [IBD]. The contribution of MtSCs to the generation of inflammatory fibroblasts during IBD is also poorly understood. We hypothesized that IBD-MtSCs are impaired and contribute to the generation of the pathological myofibroblasts in IBD.

METHODS

In a cohort of clinically and endoscopically active IBD patients and normal controls, we used quantitative RT-PCR and stem cell differentiation assays, as well as confocal microscopy, to characterize MtSCs.

RESULTS

Expression of two stem cell markers, Oct4 and ALDH1A, was increased in the inflamed IBD colonic mucosa and correlated with an increase of the mesenchymal lineage marker Grem1 in ulcerative colitis [UC], but not Crohn's disease [CD]. Increased proliferation and aberrant differentiation of Oct4+Grem1+ MtSC-like cells was observed in UC, but not in CD colonic mucosa. In contrast to normal and UC-derived MtSCs, CD-MtSCs lose their clonogenic and most of their differentiation capacities. Our data also suggest that severe damage to these cells in CD may account for the pathological PD-L1low phenotype of CD myofibroblasts. In contrast, aberrant differentiation of MtSCs appears to be involved in the appearance of pathological partially differentiated PD-L1high myofibroblasts within the inflammed colonic mucosa in UC.

CONCLUSION

Our data show, for the first time, that the progenitor functions of MtSCs are differentially impaired in CD vs UC, providing a scientific rationale for the use of allogeneic MSC therapy in IBD, and particularly in CD.