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Artemisia argyi polysaccharide gelatin microspheres were prepared by emulsification-chemical crosslinking method using gelatin as the boating material. The effects of the concentration of Artemisia argyi polysaccharide, gelatin mass fraction, oil-water ratio, and emulsifier concentration on the encapsulation rate and drug loading capacity of the microspheres were investigated. The optimal preparation prescription was determined by single-factor and response surface analysis. The morphology of Artemisia argyi polysaccharide gelatin microspheres was observed by scanning electron microscope (SEM). The slow-release effect and the inhibition of α-glucosidase and α-amylase activities were investigated by the determination of release degree. The results showed that the optimal prescription was as follows: The concentration of Artemisia argyi polysaccharide 15 mg/mL, oil-water ratio 3.8:1, emulsifier concentration 1.2% and the gelatin mass fraction 10.20%, and the encapsulation rate and drug loading capacity was 63.80% and 9.38% respectively. Under the SEM, the microspheres appeared round and the average particle size was 59.593 μm. The results of release degree showed that the cumulative release rate of Artemisia argyi polysaccharide was about 60% and 80% at 12 h in pH 2.5 (simulated gastric acid) and 7.4 (simulated intestinal fluid) media, respectively. The inhibition of α-glucosidase and α-amylase by microspheres releasing polysaccharides in pH7.4 release medium was 31.31% and 17.15%, respectively. It was demonstrated that the microspheres prepared from Artemisia argyi polysaccharide and gelatin had an enteric slow-release effect and specific in vitro hypoglycemic activity, which provided a theoretical basis for the development of the products of Artemisia argyi polysaccharide for regulating blood glucose.

Abstract Background Icariin (ICA), a main active ingredient of Herba Epimedium, could promote bone formation, inhibit bone resorption and alleviate inflammatory responses. The aim of this study was to investigate the effect of ICA on the inhibition of bacteria associated with peri-implantitis, and fabricate a calcium phosphate cement (CPC) with ICA-loaded gelatin microspheres (GMs) as a local drug delivery system efficiently promoting bone formation and alleviating inflammation. Results In this study, ICA exhibited antibacterial activity against P. gingivalis with a MIC value of 1 × 10–4 mol/L. When the concentration of ICA was 0.5 mM, the encapsulation efficiency of GMs reached the maximum value of 76.26 ± 3.97%. GMs with ICA revealed a controlled release profile, 0.5 mM ICA exhibited a higher ICA release profile than the other groups during a 21 d monitoring span. The results of SEM and XRD demonstrated successful fabrication of a calcium phosphate cement with ICA-loaded GMs. ICA released from CPC/GMs (ICA) was slower than ICA released from GMs within 10 days. CPC/GMs (ICA) exhibited antibacterial activity against P. gingivalis, but the antibacterial rate of CPC/GMs (ICA) was only 17.15 ± 6.06%. In addition, CPC/GMs (ICA) promoted the proliferation of BMSCs and significantly stimulated the differentiation and maturation of BMSCs. In vivo, H&E and Masson staining experiments demonstrated that CPC/GMs (ICA) exhibited better capacity for bone regeneration than CPC/GMs and CPC, and the expression of TNF-α and IL-1β in the tissue around CPC/GMs (ICA) was significantly lower than CPC/GMs and CPC in IHC staining (P

Background: Icariin (ICA), a main active ingredient of Herba Epimedium, could promote bone formation, inhibit bone resorption and alleviate inflammatory responses. The aim of this study was to investigate the effect of ICA on the inhibition of bacteria associated with peri-implantitis, and fabricate a calcium phosphate cement (CPC) with ICA-loaded gelatin microspheres (GMs) as a local drug delivery system efficiently promoting bone formation and alleviating inflammation. Results: In this study, ICA exhibited antibacterial activity against P. gingivalis with a MIC value of 1 × 10–4 mol/L. When the concentration of ICA was 0.5 mM, the encapsulation efficiency of GMs reached the maximum value of 76.26 ± 3.97%. GMs with ICA revealed a controlled release profile, 0.5 mM ICA exhibited a higher ICA release profile than the other groups during a 21 d monitoring span. The results of SEM and XRD demonstrated successful fabrication of a calcium phosphate cement with ICA-loaded GMs. ICA released from CPC/GMs (ICA) was slower than ICA released from GMs within 10 days. CPC/GMs (ICA) exhibited antibacterial activity against P. gingivalis, but the antibacterial rate of CPC/GMs (ICA) was only 17.15 ± 6.06%. In addition, CPC/GMs (ICA) promoted the proliferation of BMSCs and significantly stimulated the differentiation and maturation of BMSCs. In vivo, H&E and Masson staining experiments demonstrated that CPC/GMs (ICA) exhibited better capacity for bone regeneration than CPC/GMs and CPC, and the expression of TNF-α and IL-1β in the tissue around CPC/GMs (ICA) was significantly lower than CPC/GMs and CPC in IHC staining (P < 0.05). Conclusion: In this study, ICA exhibited limited antibacterial activity against bacteria associated with peri-implantitis. A composite material of calcium phosphate cement with ICA-loaded gelatin microspheres was developed, which not only promoting osteoinductivity and bone formation, but also alleviating inflammation, demonstrating its potential as a promising bone substitute material for treatment of peri-implantitis. [ABSTRACT FROM AUTHOR]

Insufficient vascularization is a major challenge in the repair of critical-sized bone defects. Deferoxamine (DFO) has been reported to play a potential role in promoting the formation of H-type blood vessels, a specialized vascular subtype with coupled angiogenesis and osteogenesis. However, whether DFO promotes the expression of H-type vessels in critical femoral defects with complete periosteal damage remains unknown. Moreover, stable drug loading systems need to be designed owing to the short half-life and high-dose toxic effects of DFO. In this study, we developed an injectable DFO-gelatin microspheres (GMs) hydrogel complex as a stable drug loading system for the treatment of critical femoral defects in rats. Our results showed that sustained release of DFO in critical femoral defects stimulated the generation of functional H-type vessels. The DFO-GMs hydrogel complex effectively promoted proliferation, formation, and migration of human umbilical vein endothelial cells in vitro. In vivo , the application of the DFO-GMs hydrogel complex expanded the distribution range and prolonged the expression time of H-type vessels in the defect area and was positively correlated with the number of osterix+ cells and new bone tissue. Topical application of the HIF-1α inhibitor PX-478 partially blocked the stimulation of H-type vessels by DFO, whereas the osteogenic potential of the latter was also weakened. Our results extended the local application of DFO and provided a theoretical basis for targeting H-type vessels to treat large femoral defects. Abundant functional blood vessels are essential for bone repair. The H-type blood vessel is a functional subtype with angiogenesis and osteogenesis coupling potential. A drug loading system with long-term controlled release was first used to investigate the formation of H-type blood vessels in critical femoral defects and promotion of bone repair. Our results showed that the application of DFO-GMs hydrogel complex expanded the distribution range and expression time of H-type vessels, and was positively correlated with the number of osteoblasts and volume of new bone tissue. These results expanded the local application approach of DFO and provide a theoretical basis for targeting H-type vessels to treat large femoral defects. [Display omitted] [ABSTRACT FROM AUTHOR]

Introduction: Reconstructing sebaceous glands is one goal of functionally healing patients who have suffered severe burns, instead of the simple pursuit of wound closure. Effective regeneration of skin appendages remains a challenge in skin wound management and research. Objective: The aim of this study was to evaluate the differentiation of adipose-derived stem cells (ADSCs) into sebaceous glands and clarified the involvement of hepatocyte growth factor (HGF) and 5α-dihydrotestosterone (5α-DHT) in this process. Methods: This study used HGF- and 5α-DHT-gelatin microspheres to treat human ADSCs and investigated the reconstruction of sebaceous glands. HGF- and 5α-DHT-gelatin microspheres were constructed using microcapsule slow-release technology. A mice full-thickness skin-wound model was established to evaluate wound healing, and hematoxylin-eosin staining was utilized to determine the skin structure. Results: In vitro analyses found that HGF- and 5α-DHT-gelatin microspheres promoted migration of and tube formation by ADSCs. Furthermore, AKT/ERK signaling, which is related to sebocyte and sweat gland epithelial-cell growth, was activated after HGF and 5α-DHT treatment. An in vivo wound healing model demonstrated that ADSCs primed with amnion-loaded HGF- and 5α-DHT-gelatin microspheres promoted wound healing and increased sebaceous gland formation compared to the control group. Conclusions: This study confirms the efficacy of ADSCs treated with amnion and HGF- and 5α-DHT-gelatin microspheres in accelerating wound healing and effectively restoring sebaceous glands. This engineered tissue provides insight into and a novel therapeutic material for burns and full-thickness skin wounds. [ABSTRACT FROM AUTHOR]

The delayed and complicated diabetic wound healing raises clinical and social concerns. The application of stem cells along with hydrogels is an attractive therapeutic approach. However, low cell retention and integration hindered the performance. Herein, gelatin microspheres were fabricated for local delivery of adipose-derived stem cells (from rats, rADSCs), and the effect of rADSCs with microspheres on diabetic wound healing was examined. Uniform, well-dispersed microspheres were fabricated using the microfluidic technique. Due to geometry differences, the proteinase degradation rate for microspheres was four times that of the bulk hydrogel. The obtained gelatin microspheres supported cell's adhesion and proliferation and provided a suitable microenvironment for rADSC survival. For in vivo animal tests, rADSCs were labeled with CM-Dil for tracking purposes. Microspheres were well embedded in the regenerated tissue and demonstrated good biocompatibility and an adaptive biodegradation rate. Histological examination revealed rADSC-loaded gelatin microspheres that significantly accelerated wound healing via promoting M2 macrophage polarization, collagen deposition, angiogenesis associated with peripheral nerve recovery, and hair follicle formation. Notably, the relative fluorescence intensity around the hair follicle was 17-fold higher than that of the blank group, indicating rADSC participated in the healing process via exosomes. Taken together, the rADSC-laden gelatin microspheres provided a promising strategy for local stem cell delivery to improve diabetic wound healing.

In this work, microspheres were developed by cross-linking glutaraldehyde in an aqueous gelatin solution with a surfactant and solvent. A poly(vinyl alcohol) (PVA) solution was produced and combined with catechin-loaded microspheres. Different microsphere concentrations (0%, 5%, 10%, and 15%) were applied to the PVA microneedles. The moisture content, particle size, swelling, and drug release percentage of microneedles were studied using various microsphere concentrations. Fourier transform infrared and scanning electron microscopy (SEM) investigations validated the structure of gelatin microspheres as well as their decoration in microneedles. The SEM scans revealed that spherical microspheres with a wrinkled and folded morphology were created, with no physical holes visible on the surface. The gelatin microspheres generated had a mean particle size of 20-30 μm. Ex vivo release analysis indicated that microneedles containing 10% microspheres released the most catechin, with 42.9% at 12 h and 84.4% at 24 h.

The major challenge in utilizing pesticides lies in identifying the precise application that would improve the efficiency of these pesticides and decline their environmental and health hazards at the same time. Such application requires the development of specific formulations that enable controlled, stimuli-responsive release of the pesticides. Gelatin is a relatively cheap material characterized by temperature-sensitivity and abundant amino acid groups, which makes it suitable for the storage and controlled release of pesticides. In this study, gelatin microspheres were prepared by emulsion and cross-linking, then they were loaded with 2,4-dichlorophenoxyacetic acid sodium (2,4-D Na) as a model herbicide. To achieve temperature-tunable release of 2,4-D Na from the microspheres, NH4HCO3 was added to the formulations at different concentrations. The prepared formulations were characterized by SEM, FTIR, and size distribution analyzes, and their drug loading capacities were determined. Based on bioassay experiments, the 2,4-D Na-NH4HCO3-loaded gelatin microspheres can effectively control the spread of dicotyledonous weeds. Therefore, the strategy proposed herein can be used to develop novel, effective herbicide formulations. [ABSTRACT FROM AUTHOR]

Diabetic wound healing remains a worldwide challenge for both clinicians and researchers. The high expression of matrix metalloproteinase 9 (MMP9) and a high inflammatory response are indicative of poor diabetic wound healing. H8, a curcumin analogue, is able to treat diabetes and is anti-inflammatory, and our pretest showed that it has the potential to treat diabetic wound healing. However, H8 is highly expressed in organs such as the liver and kidney, resulting in its unfocused use in diabetic wound targeting. (These data were not published, see Table S1 in the Supporting Information.) Accordingly, it is important to pursue effective carrier vehicles to facilitate the therapeutic uses of H8. The use of H8 delivered by macrophage membrane-derived nanovesicles provides a potential strategy for repairing diabetic wounds with improved drug efficacy and fast healing. In this study, we fabricated an injectable gelatin microsphere (GM) with sustained MMP9-responsive H8 macrophage membrane-derived nanovesicles (H8NVs) with a targeted release to promote angiogenesis that also reduces oxidative stress damage and inflammation, promoting diabetic wound healing. Gelatin microspheres loaded with H8NV (GMH8NV) stimulated by MMP9 can significantly facilitate the migration of NIH-3T3 cells and facilitate the development of tubular structures by HUVEC in vitro . In addition, our results demonstrated that GMH8NV stimulated by MMP9 protected cells from oxidative damage and polarized macrophages to the M2 phenotype, leading to an inflammation inhibition. By stimulating angiogenesis and collagen deposition, inhibiting inflammation, and reducing MMP9 expression, GMH8NV accelerated wound healing. This study showed that GMH8NVs were targeted to release H8NV after MMP9 stimulation, suggesting promising potential in achieving satisfactory healing in diabetic treatment.

Objective: The objective of this study was to evaluate the degradation characteristics and embolic effect of gelatin microspheres (GMSs) produced domestically in China through an experimental study comparing the embolization of rabbit renal arteries using GMSs and tris-acryl microspheres.Materials and Methods: Sixteen healthy adult New Zealand white rabbits were randomly divided into two groups. Group A was embolized with GMSs produced in China with a diameter of 150-200 μm (n = 8), and Group B was embolized with tris-acryl microspheres with a diameter of 100-200 μm (n = 8). The renal arteries were embolized through femoral artery puncture and catheterization. Renal artery angiography rechecks and hematoxylin and eosin staining of tissue sections were performed at 1 day, 4 days, 7 days, and 14 days after embolization, respectively, to observe vascular recanalization, degradation of microspheres, and embolic effect.Results: Group A: Digital subtraction angiography showed complete recanalization at 14 days. The changes in embolic necrotic areas at different time points after embolization were similar in the two groups. At 4 days after embolization, changes in glomerular structure were observed in the kidney on the embolic side. At 7 days after embolization, atrophy, degeneration, and necrosis of the glomeruli, as well as degeneration and inflammatory cell infiltration of the renal tubules, were observed in the kidney on the embolic side. At 14 days after embolization, extensive atrophy and hyalinization of the glomeruli were observed, and local renal tissue showed patchy fibrosis with calcification of internal tissue. Hyperplasia of fibrillar connective tissue was observed in the renal interstitium.Conclusion: The GMSs produced domestically in China can be completely degraded after embolizing blood vessels for 14 days. The GMSs are similar to tris-acryl microspheres in arterial embolization effect and are safe and effective. [ABSTRACT FROM AUTHOR]

The aim of this study was to prepare a promising biomaterial for bone tissue repair and regeneration. The Strontium – calcium sulfate hemihydrate (Sr-α-CaS) scaffold incorporating gelatin microspheres (GMs) encapsulated with Ginsenoside Rg1 (Rg1) was designed. The scaffolds of Rg1/GMs/Sr-α-CaS showed sustained release of Rg1, good biocompatibility and ability of promoting osteogenic differentiation and angiogenesis in vitro. The scaffolds were implanted into animal model of cranial bone defect to characterize bone tissue repair and regeneration in vivo. From the images of Micro-CT, it was obvious that the most bone tissue was formed in Rg1/GMs/Sr-α-CaS group in 12 weeks. New bone structure, collagen and mineralization were analyzed with staining of HE, Masson and Safranin O-Fast green and showed good distribution. The expression of osteocalcin of Rg1/GMs/Sr-α-CaS indicated new bone formation in defect site. The results revealed that synergy of Rg1 and Sr showed the best effect of bone repair and regeneration, which provided a new candidate for bone defect repair in clinic.

Gelatin, a natural polymer, provides excellent tissue compatibility for use in tissue rehabilitation. Bioactive glasses (BAG) offer superior capacity in stimulating a bioactive response but show high variability in uptake and solubility. To tackle these drawbacks, a combination of gelatin with BAG is proposed to form composites, which then offer a synergistic response. The cross-linked gelatin structure’s mechanical properties are enhanced by the incorporation of the inorganic BAG, and the rate of BAG ionic supplementation responsible for bioactivity and regenerative potential is better controlled by a protective gelatin layer. Several studies have demonstrated the cellular benefits of these composites in different forms of functional modification such as doping with zinc or incorporation of zinc such as ions directly into the BAG matrix. This review presents a comprehensive perspective on the individual characteristics of BAG and gelatin, including the synthesis and mechanism of action. Further, adaptation of the composite into various applications for bone tissue engineering is discussed and future challenges are highlighted.

For cartilage tissue engineering, several in vitro culture methodologies have displayed potential for the chondrogenic differentiation of mesenchymal stem cells (MSCs). Micromasses, cell aggregates or pellets, and cell sheets are all structures with high cell density that provides for abundant cell-cell interactions, which have been demonstrated to be important for chondrogenesis. Recently, these culture systems have been improved via the incorporation of growth factor releasing components such as degradable microspheres within the structures, further enhancing chondrogenesis. Herein, we incorporated different amounts of gelatin microspheres releasing transforming growth factor β1 (TGF-β1) into micromasses composed of human periosteum derived cells (hPDCs), an MSC-like cell population. The aim of this research was to investigate chondrogenic stimulation by TGF-β1 delivery from these degradable microspheres in comparison to exogenous supplementation with TGF-β1 in the culture medium. Microscopy showed that the gelatin microspheres could be successfully incorporated within hPDC micromasses without interfering with the formation of the structure, while biochemical analysis and histology demonstrated increasing DNA content at week 2 and accumulation of glycosaminoglycan and collagen at weeks 2 and 4. Importantly, similar chondrogenesis was achieved when TGF-β1 was delivered from the microspheres compared to controls with TGF-β1 in the medium. Increasing the amount of growth factor within the micromasses by increasing the amount of microspheres added did not further improve chondrogenesis of the hPDCs. These findings demonstrate the potential of using cytokine releasing, gelatin microspheres to enhance the chondrogenic capabilities of hPDC micromasses as an alternative to supplementation of the culture medium with growth factors. Gelatin microspheres are utilized for growth factor delivery to enhance chondrogenesis of mesenchymal stem cells (MSCs) in high cell density culture systems. Herein, we employ a new combination of these microspheres with micromasses of human periosteum-derived cells, which possess ease of isolation, excellent expansion potential, and MSC-like differentiation capabilities. The resulting localized delivery of transforming growth factor β1 increases glycosaminoglycan and collagen production within the micromasses without exogenous stimulation in the medium. This unique combination is able to drive chondrogenesis up to similar levels as seen in micromasses that do receive exogenous stimulation. The addition of growth factor releasing microspheres to high cell density micromasses has the potential to reduce costs associated with this strategy for cartilage tissue engineering. [ABSTRACT FROM AUTHOR]

Gelatin, as natural macromolecular material, has been used in biomedical fields widely. In this study, various injectable gelatins A, B, and their compound AB microsphere-based gels (A-GMGs, B-GMGs and AB-GMGs) were prepared through water-in-oil emulsion method for hemostasis, and the effects of blood coagulation in vitro and surgical hemostasis (a deep liver wound model) in vivo were evaluated. Furthermore, the influences of gelatin sorts, the size of microsphere, zeta potential (ZP) and viscoelastic properties on hemostasis were also assessed. Results showed that the gelatin microspheres (GMs) exhibited smooth surface, good sphericity and the particle size of a rough normal distribution. GMs carried negative charges and their electronegativity was stronger than that of gelatin A (GA) and gelatin B (GB) raw materials. Rheological analysis showed that a decreasing particle size of the microspheres led to stronger gel strength, and solid-like gels were exhibited under low stress conditions and liquid-like gels were exhibited under high stress conditions. The blood clotting time of B-GMGs was within 60 s, which exhibited a significantly higher blood clotting effect compared with control groups. The hemostasis assay in vivo showed that the gels had better hemostatic effect on a deep liver wound bleeding model compared with control groups, especially B-GMGs. However, in vivo and vitro hemostatic experiments, particle size of GMs had no obvious influence on the hemostatic effect of the gels. In addition, the CCK-8 assay of bone marrow mesenchymal stem cells of murine (mMSCs) indicated non-cytotoxicity of GMs for cells. These results demonstrated that the gelatin microsphere-based gels (GMGs) had potential to be an effective hemostatic material for intracavitary and deep wound bleeding in surgery. [ABSTRACT FROM AUTHOR]

Hai Zhuang,1–3 Shoushan Bu,1 Lei Hua,1 Mohammad A Darabi,2,3 Xiaojian Cao,4 Malcolm Xing2,3 1Department of Stomatology, The First Affiliated Hospital with Nanjing Medical University, Nanjing, Jiangsu Province, People’s Republic of China; 2Department of Mechanical Engineering, Biochemistry & Medical Genetics, 3Children’s Hospital Research Institute of Manitoba, University of Manitoba, Winnipeg, MB, Canada; 4Department of Orthopedics, The First Affiliated Hospital with Nanjing Medical University, Nanjing, Jiangsu Province, People’s Republic of China Abstract: In this study, we fabricated glial cell-line derived neurotrophic factor (GDNF)-loaded microspheres, then seeded the microspheres in gelatin-methacrylamide hydrogel, which was finally integrated with the commercial bilayer collagen membrane (Bio-Gide®). The novel composite of nerve conduit was employed to bridge a 10 mm long sciatic nerve defect in a rat. GDNF-loaded gelatin microspheres had a smooth surface with an average diameter of 3.9±1.8 µm. Scanning electron microscopy showed that microspheres were uniformly distributed in both the GelMA gel and the layered structure. Using enzyme-linked immunosorbent assay, in vitro release studies (pH 7.4) of GDNF from microspheres exhibited an initial burst release during the first 3 days (18.0%±1.3%), and then, a prolonged-release profile extended to 32 days. However, in an acidic condition (pH 2.5), the initial release percentage of GDNF was up to 91.2%±0.9% within 4 hours and the cumulative release percentage of GDNF was 99.2%±0.2% at 48 hours. Then the composite conduct was implanted in a 10 mm critical defect gap of sciatic nerve in a rat. We found that the nerve was regenerated in both conduit and autograft (AG) groups. A combination of electrophysiological assessment and histomorphometry analysis of regenerated nerves showed that axonal regeneration and functional recovery in collagen tube filled with GDNF-loaded microspheres (GM + CT) group were similar to AG group (P>0.05). Most myelinated nerves were matured and arranged densely with a uniform structure of myelin in a neat pattern along the long axis in the AG and GM + CT groups, however, regenerated nerve was absent in the BLANK group, left the 10 mm gap empty after resection, and the nerve fiber exhibited a disordered arrangement in the collagen tube group. These results indicated that the hybrid system of bilayer collagen conduit and GDNF-loaded gelatin microspheres combined with gelatin-methacrylamide hydrogels could serve as a new biodegradable artificial nerve guide for nerve tissue engineering. Keywords: controlled release of GDNF, gelatin microspheres, biodegradable nerve conduit, gelatin-methacrylamide hydrogel, sciatic nerve regeneration

Abstract The preparation and characterization of magnetic microspheres based on gelatin for use in drug delivery systems are reported. Sugars were employed as crosslinking agents and type A gelatin and type B gelatin were compared to prepare microspheres by water-in-oil emulsion. The influence of gelatin and sucrose concentration, temperature and stirring speed on microbeads’ characteristics was studied. The gelatin concentration and stirring speed were the parameters directly associated with the particle sizes. We found no relevant difference between the use of type A and type B gelatin. In addition, the gelatin crosslinking study revealed that sucrose is not a crosslinking agent but fructose can crosslink the protein chains when the reaction medium has pH 9. The size of the microspheres varied from 5 to 60 μm as measured by optical microscopic images. Doxorubicin adsorption and release were successfully performed using the microspheres crosslinked with fructose under the action of an external magnetic field. It was observed that the microspheres absorbed 69% of the doxorubicin that was in solution. After 24 h, about 45% of the DOX was displaced from microspheres to saline medium in the free form in the solution.

Gelatin microspheres were discussed as a scaffold material for bone tissue engineering, with the advantages of its porosity, biodegradability, biocompatibility, and biosafety highlighted. This review discusses how bone regeneration is aided by the three fundamental components of bone tissue engineering-seed cells, bioactive substances, and scaffold materials-and how gelatin microspheres can be employed for in vitro seed cell cultivation to ensure efficient expansion. This review also points out that gelatin microspheres are advantageous as drug delivery systems because of their multifunctional nature, which slows drug release and improves overall effectiveness. Although gelatin microspheres are useful for bone tissue creation, the scaffolds that take into account their porous structure and mechanical characteristics might be difficult to be created. This review then discusses typical techniques for creating gelatin microspheres, their recent application in bone tissue engineering, as well as possible future research directions.

In this study, a kind of antibacterial collagen (Coll)/cellulose nanocrystals (CNCs) scaffolds was prepared and characterized, which can be applied in skin trauma as a promising dressing. In order to achieve the goal of antibacterial function for a period of long time, the Gentamycin sulfate (GS) was absorbed in the prepared gelatin microsphere (GMs) then doped in the porous Coll-CNCs freeze-drying scaffold. The CNCs had a width of 20-40 nm and length of 150-350 nm from electron microscopy (TEM), retained the basic chemical structure of cellulose observed from Fourier transform infrared, and increased the machinery properties of Coll scaffold from thermal property analysis. From the SEM, the mean pore size of the compound scaffolds was about 120 μm with or without GMs. The in vitro release profile of GS showed a sustained release of this GS/GMs/Coll-CNCs composite scaffold. The biological compatibility experiments showed the composite scaffold low cellular cytotoxicity of NIH-3T3 cells. The significant inhibition zones indicated the antibacterial efficacy of the composite scaffold against Escherichia coli and Staphylococcus aureus. [ABSTRACT FROM AUTHOR]

Objectives: To investigate the therapeutic effect of gelatin microspheres containing different concentrations of calcitonin gene-related peptide (CGRP) or substance P on repairing bone defects in a rabbit osteoporosis model. Results: Gelatin microspheres containing different concentrations of CGRP or substance P promoted osteogenesis after 3 months in a rabbit osteoporotic bone defective model. From micro-computed tomography imaging results, 10 nM CGRP was optimal for increasing the trabecular number and decreasing the trabecular bone separation degree; similar effects were observed with the microspheres containing 1 µM substance P. Histological analysis showed that the gelatin microspheres containing CGRP or substance P, regardless of the concentration, effectively promoted osteogenesis, and the highest effect was achieved in the groups containing 1 µM CGRP or 1 µM substance P. Conclusions: Gelatin microspheres containing CGRP or substance P effectively promoted osteogenesis in a rabbit osteoporotic bone defect model dose-dependently, though their effects in repairing human alveolar ridge defects still need further investigation. [ABSTRACT FROM AUTHOR]

Intraarticular administration of microspheres containing non-steroidal antiinflammatory drugs is beneficial in the treatment of rheumatoid arthritis. Microspheres could localize drug at the site of administration and control its release, resulting in improved therapeutic effects and decreased side effects. Therefore, the objective of the present study was to prepare controlled release meloxicam-loaded gelatin microspheres and evaluate the effect of various variables on their properties. Meloxicam-loaded microspheres were prepared by emulsion-congealing-chemical cross-linking method. Different amounts of polymer, emulsifier and crosslinking agent, as formulation variables, were evaluated. Microspheres were characterized in terms of yield value, encapsulation efficiency and the drug release pattern. The particle size, surface morphology and thermal behaviour of microspheres were also investigated. According to the results, using glutaraldehyde as a cross-linking agent resulted in spherical microspheres with the yield value of 63-96% and encapsulation efficiency of 23-63%. The optimum formulation with the mean particle size of about 57 μm, showed slow drug release profile (64%) throughout 48 h. An appropriate polymer:cross-linker ratio must be used to obtain suitable particles with acceptable controlled released behaviour. In summary the results of the present study supported the preparation of sustained release meloxicam-loaded microspheres using emulsion-congealing method along with the potential application of glutaraldehyde in improving the physical properties of prepared particles as well as the release profile of this low water soluble drug. [ABSTRACT FROM AUTHOR]

Objective: At present, there is an urgent need to develop a novel and practical therapeutic approach to accelerate the healing of acute wounds. Mesenchymal stem cell (MSC)-based therapy is emerging as a promising therapeutic approach for acute skin wounds. However, there are still challenges in clinical application of this strategy, such as low survivability, low retention time, and less engraftment in skin wounds. Approach: Wharton's jelly mesenchymal stem cells (WJMSCs) were seeded into three-dimensional (3D) gelatin microspheres (GMs) to identify the biocompatibility of GMs. WJMSCs were embedded in GMs and then encapsulated with Pluronic F-127 (PF-127) and sodium ascorbyl phosphate (SAP) combination to transplant onto acute full-thickness skin wound in mice. Histology, immunohistochemistry, and immunofluorescence assay were used to investigate the skin wound healing, dermis regeneration, collagen deposition, cell proliferation, and neovascularization. Results: Three-dimensional GM had strong biocompatibility, compared with two-dimensional adherent culturing, GM loading increased the cell viability and proliferation ability of WJMSCs. WJMSCs+GM+PF-127+SAP transplantation increased skin wound healing rate, dermis regeneration, and type III collagen deposition through improving macrophage polarization, cell proliferation, neovascularization, cell retention, and engraftment at skin wound site. Innovation: The effective 3D encapsulation technology for WJMSCs solved the main problems of cell activity and residence time during MSC transplantation. WJMSCs+GM+PF-127+SAP transplantation will be a new and effective MSC biomaterials-based therapeutic strategy for acute skin traumatic wounds. Conclusion: WJMSCs+GM+PF-127+SAP transplantation facilitated acute full-thickness skin wound healing and regeneration and might be a new and effective therapy for acute skin traumatic wounds.

Purpose: High dosage and repeated ingestion of antibiotics in the treatment of pneumonia lead to inappropriate disposition of the drug and thus increase undesirable effects. Hence, this study was intended to achieve high levofloxacin concentration in lungs by targeted levofloxacin gelatin microspheres (LGMs). Methods: The optimized LGM prepared by emulsion method was characterized for particle size, drug encapsulation efficiency, in vitro study, X-ray diffraction (XRD), and stability studies. The in vivo lung targeting efficiency parameters such as intake rate ( r ), targeting efficacy ( t ), overall drug targeting efficacy ( T ), percentage of drug distributed to lungs ( j), and ratio of peak concentration ( C ) were investigated. Results: The mean particle size ranged from 6.28 to 19.72 μm, which can get deposited in lungs by mechanical entrapment. The curve fitting analysis showed significance for Koresmeyer-Peppas model ( R-square = 0.9959). The levofloxacin area under the curve (AUC; 899.62 μg h mL) and r (5.74) for lung were higher and statistically significant in LGM group. Compared with spleen and liver, the t in mice lung increased by a factor of 33.45 and ∼12.74, respectively. The targeting ratio of LGM increased by a factor of 26.22 (compared to spleen) and ∼10.58 (compared to liver). Subsequently by a factor of 4.63, C in lung was higher in LGM-treated mice. An overall 87.14 % of the drug was distributed to lungs when administrated as LGM formulation. The histopathology confirmed tissue tolerability. Conclusions: The gelatin microsphere allows for surface modification, and mechanically entrapped in endothelial capillary of the lung further increases affinity leading to higher levofloxacin concentration in lungs, which helps in optimizing the therapeutic efficacy in the treatment of pneumonia. [ABSTRACT FROM AUTHOR]

Previous research has raised substantial controversy over the synergistic effects of exogenous growth factors, BMP-2 and bFGF, when used together for the treatment of bony defects. Thus, this study evaluated the effects of BMP-2 and bFGF at specified dose ratio composited with n-HA/PU40, a porous scaffold material, for repairing femoral defect in rats. Four weeks after implantation of this composite system, tissue specimens were collected for histological, immunohistochemical examinations, and µ-CT scanning. The results showed that the group DUAL/BMSCs with both the factors had better effect on repairing bone defects than the other four groups in terms of new bone formation and bone-scaffold bonding, suggesting crosstalk between these growth factors during early bone regeneration. This work demonstrates that provided that there is effective contact between cells and active proteins in the defect area, the controlled release of bFGF and BMP-2 have positive synergistic effects on early bone formation in the defect area. © 2015 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 104A: 659-668, 2016. [ABSTRACT FROM AUTHOR]

Articular cartilage has restricted self-regenerative capacity; therefore, treatment of cartilage lesions is a great challenge in the field of orthopedics. In the present study, we evaluate the enhancing effect of a transforming growth factor-beta 1 (TGF-β1)-immobilized scaffold, fabricated by incorporating TGF-β1-loaded gelatin microspheres into PLGA framework, on the differentiation of adipose-derived stem cells (ASCs) into chondrocytes. Significant increase in cell proliferation was observed in the TGF-β1-immobilized PLGA-gelatin scaffold, as compared with the ASC-seeded non-TGF-β1-immobilized PLGA-gelatin scaffold. When chondrogenic differentiation of ASCs was evaluated for both constructs, sulfated glycosaminoglycan (sGAG) content was significantly higher in the TGF-β1-immobilized scaffold. This study showed that ASCs containing the TGF-β1-immobilized scaffold better promoted cartilage regeneration in defective articular cartilage, which is assessed by histological observation. Based on the above results, we conclude that TGF-β1-immobilized PLGA-gelatin scaffold seeded with ASCs considerably enhances the quality of the tissue-engineered cartilage, therefore, advancing the field of cartilage tissue engineering. [ABSTRACT FROM AUTHOR]

Tissue-engineered dermis is thought to be the best treatment for skin defects; however, slow vascularization of these biomaterial scaffolds limits their clinical application. Exogenous administration of angiogenic growth factors is highly desirable for tissue regeneration. In this study, biodegradable gelatin microspheres (GMs) containing basic fibroblast growth factor (bFGF) were fabricated and incorporated into a porous collagen/cellulose nanocrystals (CNCs) scaffold, as a platform for long-term release and consequent angiogenic boosting. The physicochemical properties of these scaffolds were examined and the in vitro release pattern of bFGF from scaffolds was measured by ELISA. Collagen/CNCs scaffolds with and without bFGF-GMs were incubated with human umbilical vein endothelial cells for 1 week, results showed that the scaffolds with bFGF-GMs significantly augmented cell proliferation. Then, four different groups of scaffolds were implanted subcutaneously into Sprague–Dawley rats to study angiogenesis in vivo via macroscopic observation, and hematoxylin and eosin and immunohistochemical staining. The results suggested that the collagen/CNCs/bFGF-GMs scaffolds had a significantly higher number of newly formed and mature blood vessels, and the fastest degradation rate. This study demonstrated that collagen/CNCs/bFGF-GMs scaffolds have great potential in skin tissue engineering. [ABSTRACT FROM AUTHOR]

Introduction The aim of this study was to investigate the effects of 131I gelatin microspheres (131I-GMS) on human breast cancer cells (MCF-7) in nude mice and the biodistribution of 131I-GMSs following intratumoral injections. Methods A total of 20 tumor-bearing mice were divided into a treatment group and control group and received intratumoral injections of 2.5 mci 131I-GMSs and nonradioactive GMSs, respectively. Tumor size was measured once per week. Another 16 mice received intratumoral injections of 0.4 mci 131I-GMSs and were subjected to single photon emission computed tomography (SPECT) scans and tissue radioactivity concentration measurements on day 1, 4, 8 and 16 postinjection. The 20 tumor-bearing mice received intratumoral injections of 0.4 mci [131I] sodium iodide solution and were subjected to SPECT scans and intratumoral radioactivity measurements at 1, 6, 24, 48 and 72 h postinjection. The tumors were collected for histological examination. Results The average tumor volume in the 131I-GMSs group on post-treatment day 21 decreased to 86.82 ± 63.6%, while it increased to 893.37 ± 158.12% in the control group (P < 0.01 vs. the 131I-GMSs group). 131I-GMSs provided much higher intratumoral retention of radioactivity, resulting in 19.93 ± 5.24% of the injected radioactivity after 16 days, whereas the control group retained only 1.83 ± 0.46% of the injected radioactivity within the tumors at 1 h postinjection. Conclusions 131I-GMSs suppressed the growth of MCF-7 in nude mice and provided sustained intratumoral radioactivity retention. The results suggest the potential of 131I-GMSs for clinical applications in radiotherapy for breast cancer. [ABSTRACT FROM AUTHOR]

Abstract: Despite advances in burn treatment, burn infection remains a major cause of morbidity and mortality. In this study, an antibacterial silk fibroin (SF) scaffold for burn treatment was designed; gelatin microspheres (GMs) were impregnated with the antibiotic gentamycin sulfate (GS), and the GS-impregnated GMs were then embedded in a SF matrix to fabricate GS/GM/SF scaffolds. The developed GS/GM/SF scaffolds could serve as a dermal regeneration template in full-thickness burns. The average pore size and porosity of the GS/GM/SF scaffolds were 40–80μm and 85%, respectively. Furthermore, the drug release rate of the scaffolds was significantly slower than that of either GS/GM or GS/SF scaffolds. And the composite scaffold exhibited stronger antimicrobial activities against Escherichia coli, Staphylococcus aureus and Pseudomonas aeruginosa. Hence, we evaluated the wound-healing effects and antibacterial properties of the GS/GM/SF scaffolds in a rat full-thickness burn infection model. Over 21days, the GS/GM/SF scaffolds not only significantly reduced burn infection by P. aeruginosa but also accelerated the regeneration of the dermis and exhibited higher epithelialization rates than did GS/SF and SF scaffolds. Thus, GS/GM/SF scaffolds are potentially effective for treatment of full-thickness infected burns, and GS/GM/SF scaffolds are a promising therapeutic tool for severely burned patients. [Copyright &y& Elsevier]

One of the advances in biotechnology has been the development of the capability to produce large quantities of highly purified polypeptides and proteins. Unfortunately, the circulatory half-lives of many of these agents are short, usually of the order of minutes and the time required for a response in tissues is usually long compared to the half-life. Hence, there is always demand for polymeric systems which can deliver the proteins for prolonged period and also to protect the molecules from degradation. The present work was attempted to develop heparin-functionalized gelatin microspheres (HMS) to deliver heparin-binding growth factors particularly for wound-healing applications. The heparin conjugation was carried out using EDC/NHS coupling protocol. Heparin-binding EGF-like growth factor (HB-EGF) was loaded in HMS and its in vitro release behaviour in an environment with or without proteases was studied. The bioactivity of the HB-EGF released from the microspheres was assessed using NIH 3T3 mouse embryonic fibroblast culture. The extent of heparin modification was found to be 1.97 μmol/g of HMS and demonstrated significant protection against enzymatic degradation and sustained release of HB-EGF for more than 10 days. The bioactivity of HB-EGF released from the HMS was retained during the observed release period. The HMS was also found to be non-toxic as determined by calcein AM fluorescent staining. The overall study suggests that the HMS could be used as a growth factor's delivery component in tissue engineering scaffolds particularly for wound-healing applications. [ABSTRACT FROM AUTHOR]

The aim of this study was to prepare ganciclovir (GCV)-loaded cross-linked gelatin microspheres by spray-drying method. The microspheres were characterized in terms of particle size, surface morphology, loading efficiency, thermal behavior, physical characteristics, swelling properties, and the release profile in vitro. The major process and formulation parameters were optimized to obtain smaller particles with high loading capacity. The physical state examination confirmed the molecular-level dispersion of drug in the polymer. The loading efficiency determined by high-performance liquid chromatography (HPLC) was around 68%. The in vitro release experiments revealed that the GCV released from the gelatin microspheres was related to the extent of swelling, which was proportional to the drug-to-polymer ratio. These results suggest that cross-linked gelatin microspheres could be a suitable drug-delivery system for GCV. [Figure not available: see fulltext.] [ABSTRACT FROM AUTHOR]

Purpose: To evaluate the embolic effect and degradability of gelatin microspheres (GMS) using various degrees of cross-linkage and particle sizes in rabbit renal artery embolization. Methods: Four types of GMS were used, as follows: 2 types of cross-linkage and 2 types of particle size. Twenty-four rabbits (6 in each group) were used for the renal artery embolization. Renal angiography was performed before and after embolization of right renal artery. Follow-up renal angiography was performed 2 days ( n = 2), 5 days ( n = 2), and 15 days ( n = 2) after embolization in each group, and then kidneys were removed for histopathological evaluation. Vascular areas of the angiography were measured by Image J software, and the reperfusion rate was calculated. In renal specimens, residual GMS were checked and the degree of degradation was classified according to a 4-point scale. Results: The mean amounts of large- and small-particle-size GMS injected were 15.0 and 34.3 mg, respectively. Tissue necrosis was confirmed in each group; however, no difference was observed among groups. Renal reperfusion was observed more with small GMS than with large GMS. Renal reperfusion was also observed more with low cross-linked GMS than with high cross-linked GMS. In histopathological specimens, large GMS were confirmed in lobar artery, and small GMS were confirmed in lobular artery. Low cross-linked GMS completely degraded 15 days after embolization. In contrast, high cross-linked GMS were persistent 15 days after embolization. Conclusion: Degree of cross-linkage and particle size affected degradability and reperfusion. [ABSTRACT FROM AUTHOR]

Oral and parenteral formulations are challenging to produce therapeutic concentration of flurbiprofen in the joints. This encourages for the development of formulation for long term drug retention in the joint through intra-articular (i. a.) administration. In this study, genipin cross-linked gelatin microspheres of flurbiprofen were prepared for i. a. delivery. The microspheres were prepared using emulsification-homogenization-cross-linking method by changing the experimental variables such as concentration of cross-linker, cross-linking time and cross-linking temperature. The microspheres showed drug entrapment up to 76.19% with a mean particle size range of 5.91-8.19 µm. The degree of cross-linking and water-soluble fraction were 8.27-59.33% and 12.29-81.23%, respectively. SEM confirmed smooth surface and spherical shape of the microspheres. FTIR and 13C-NMR confirmed cross-linking of gelatin by genipin. No chemical change in encapsulated drug was observed by FTIR and TGA. DSC and XRD indicated the molecular dispersion of drug within microspheres. Optimized microspheres could prolong the drug release for more than 108 h with anomalous transport. Histopathology confirmed the biocompatibility of microspheres in the rat (Wistar) knee joint. After 96 h of i. a. injection, significant higher amount (42.56%) of administered drug in cross-linked microspheres was recovered than uncross-linked microspheres (8.27%) confirming better drug retention efficiency ( p < 0.01). [ABSTRACT FROM AUTHOR]

Porous scaffolds with graded pores are crucial to osteochondral regeneration. In this study, a technique combining solution casting with gelatin-microsphere template leaching has been developed to produce poly(L-lactide-co-glycolide) (PLGA) scaffolds with graded pores. The traditional emulsification and solvent extraction method was improved by using the gradient ethanol/water solutions to extract water to prepare gelatin microspheres with a smooth surface without the use of any surfactant. Gelatin microspheres with different diameters were in sequence put into a custom-made cylindrical Teflon mold and bonded together to obtain gelatin-microsphere templates. By using the gelatin-microsphere templates as porogen, PLGA scaffolds with graded pore size across the cylindrical axis were prepared. The porosity of the scaffold was as high as 95%. The pore size effect on osteoblasts was studied. The results showed that the graded scaffolds possessed good biocompatibility for osteoblast growth. During the 14 days culture, the cell proliferation of all the three pore layers displayed the trend of increasing. The proliferation rate of the large pore layer was lower than the other two layers. However, the difference of alkaline phosphatase activity on the three pore layers was not statistically significant. We assumed that it was probably because of the hydrophobicity and the short culture time. It was demonstrated that gradient ethanol/water solutions provided a simple way to prepared gelatin microspheres. The graded scaffolds would provide potential application for osteochondral regeneration. [ABSTRACT FROM AUTHOR]

Abstract: The utility of hydrogels for regenerative medicine can be improved through localized gene delivery to enhance their bioactivity. However, current systems typically lead to low-level transgene expression located in host tissue surrounding the implant. Herein, we investigated the inclusion of macropores into hydrogels to facilitate cell ingrowth and enhance gene delivery within the macropores in vivo. Macropores were created within PEG hydrogels by gelation around gelatin microspheres, with gelatin subsequently dissolved by incubation at 37 °C. The macropores were interconnected, as evidenced by homogeneous cell seeding in vitro and complete cell infiltration in vivo. Lentivirus loaded within hydrogels following gelation retained its activity relative to the unencapsulated control virus. In vivo, macroporous PEG demonstrated sustained, elevated levels of transgene expression for 6 weeks, while hydrogels without macropores had transient expression. Transduced cells were located throughout the macroporous structure, while non-macroporous PEG hydrogels had transduction only in the adjacent host tissue. Delivery of lentivirus encoding for VEGF increased vascularization relative to the control, with vessels throughout the macropores of the hydrogel. The inclusion of macropores within the hydrogel to enhance cell infiltration enhances transduction and influences tissue development, which has implications for multiple regenerative medicine applications. [Copyright &y& Elsevier]

Gelatin microspheres containing 5-fluorouracil (5-FU) were prepared by water/oil (W/O) emulsion and chemical cross-linking with glutaraldehyde. In order to obtain microspheres with an appropriate drug release profile, the effects of cross-linking time and amount of cross-linking agent on the swelling properties of microspheres and their release profile were investigated. Gelatin microspheres prepared with a larger amount of cross-linking agent, or after longer cross-linking time, showed a reduced swelling ratio in aqueous media. The in vitro release pattern of 5-FU from gelatin microspheres showed a biphasic profile and the release rates were reduced upon increasing the amount of cross-liking agent and prolonging the cross-linking time. [ABSTRACT FROM PUBLISHER]