Polycaprolactone Microspheres Research Articles

Highly porous polycaprolactone microspheres for skeletal repair promote a mature bone cell phenotype in vitro.

Improving our ability to treat skeletal defects is a critical medical challenge that necessitates the development of new biomaterials. One promising approach involves the use of degradable polymer microparticles with an interconnected internal porosity. Here, we employed a double emulsion to generate such round microparticles (also known as microspheres) from a polycaprolactone-based polymerised high internal phase emulsion (polyHIPE). These microspheres effectively supported the growth of mesenchymal progenitors over a 30-day period, and when maintained in osteogenic media, cells deposited a bone-like extracellular matrix, as determined by histological staining for calcium and collagen. Interestingly, cells with an osteocyte-like morphology were observed within the core of the microspheres indicating the role of a physical environment comparable to native bone for this phenotype to occur. At later timepoints, these cultures had significantly increased mRNA expression of the osteocyte-specific markers dentin matrix phosphoprotein-1 (Dmp-1) and sclerostin, with sclerostin also observed at the protein level. Cells pre-cultured on porous microspheres exhibited enhanced survival rates compared to those pre-cultured on non-porous counterparts when injected. Cells precultured on both porous and non-porous microspheres promoted angiogenesis in a chorioallantoic membrane (CAM) assay. In summary, the polycaprolactone polyHIPE microspheres developed in this study exhibit significant promise as an alternative to traditional synthetic bone graft substitutes, offering a conducive environment for cell growth and differentiation, with the potential for better clinical outcomes in bone repair and regeneration.

Injectable, oxygen-releasing, thermosensitive hydrogel promotes vascularized bone formation with prolonged oxygen delivery and improved osteoinductivity

The failure or delay in healing of critical bone defects is primarily due to early local anoxic conditions and reduced osteogenic activity. In this research, we integrated calcium peroxide (CPO) embedded polycaprolactone (PCL) microspheres and osteoinductive nanoparticles (Hydroxyapatite/Laponite) into a thermosensitive hydrogel (Pluronic F127), thereby formulating an injectable oxygen-releasing osteogenic thermosensitive hydrogel. Notably, the oxygen-releasing microspheres (ORMs) within the composite hydrogel provide stable oxygen release for up to 21 days, ensuring the survival, migration, and bioactivity of both mesenchymal stem cells and endothelial cells under anoxic conditions. Additionally, the composite hydrogel significantly augments the osteogenic potential of bone marrow mesenchymal stem cells by providing a biomimetic microenvironment with the incorporation of nano-hydroxyapatite/laponite. Ultimately, the injectable composite hydrogel successfully stimulated bone regeneration within a cranial defect in a rat model after 8 weeks, with enhanced vascularization and bone quality. The engineered hydrogel provides a minimally invasive approach to stimulate bone regeneration with a sustained oxygen supply and osteogenic microenvironment provision, underlining its potential for treating critical bone defects.

Non-invasive Thermohydrodynamic Approach for Fast Cell Manipulation at the Microscale

Thermal gradients have emerged as a promising technique for manipulating and sorting biological material at the microscale, holding considerable potential in lab-on-a-chip technology. Herein, we propose a non-invasive thermohydrodynamic approach for fast cell manipulation using a microfluidic open-to-air device. Cell discrimination is achieved by simply changing the temperature gradient toward the control of the convective effect on their displacement. First, the size and morphology/roughness-based motion capabilities were modeled using polystyrene (PS) microparticles with different sizes (5 and 20 μm) and polycaprolactone (PCL) microspheres, respectively. Computational fluid dynamics simulations of the generated flow were also carried out to demonstrate the influence of both the thermohydrodynamic and Marangoni effects in the PS particle displacement, where the thermally induced convective effect was not enough to move the microparticles inside the channel, but the combination of thermally induced convection together with the Marangoni effect. Indeed, small particles (5 μm) followed a full convective path, whereas the bigger ones (20 μm) exhibited a rolling motion on the substrate from the cold side to the hot side. Also, the relationship between in-flow speed and PCL (≈ 20 μm) surface roughness confirmed the driving force of this convection-based approach. Then, the microfluidic device was successfully used to separate Henrietta Lacks cancer cells (HeLa) from red blood (RBCs) and fibroblast (HFF-1) cells. To this end, thermal gradients were tailored to achieve the desired thermohydrodynamic effect, showing a highly versatile performance. Both cell models (HeLa-RBCs and HeLa-HFF-1), due to rationale tweaking of the imposed temperature gradients (ΔT = 10 K, 303–293 K, and ΔT = 5 K, 303–298 K), were efficiently separated in less than 5 and 60 s, respectively; with excellent cell viabilities. The proposed microfluidic approach holds considerable promise for thermohydrodynamic sorting and manipulation of biological material by non-invasive methods using portable instrumentation. The potential parallelization of the thermal-convective approach opens new avenues for early disease diagnosis (liquid biopsies) or the study of biological systems, even at physiological temperatures with a potential impact in cell (organ)-on-a-chip technologies.

Using embossing ice particulate method to prepare polyvinyl alcohol/pullulan hydrogels with surface open pores loaded with microspheres for breast cancer treatment

In the post-operative treatment of breast cancer, early prevention of locoregional recurrence is crucial to avoid metastasis of cells from leftover microtumor tissues. The limitations in conventional drug delivery systems show a growing clinical demand for disease-specific drug-releasing systems. This study explores a novel poly(vinyl alcohol)/pullulan (PVA/PUL) hydrogel system for local drug delivery in post-operative breast cancer treatment. Hydrogel was produced by combination of lyophilization and embossing ice particulate techniques to create microspheres loaded open pores on the hydrogel surface for localized release of doxorubicin-loaded polycaprolactone microspheres (DOX-PCL-MSs). PVA/PUL hydrogel was successfully crosslinked with glutaraldehyde and stabilized hydrogel structure has possessed slow degradation rate and increasing water retention through 12 days. Release of DOX after 7 and 16 days from DOX-PCL-MSs loaded hydrogels were slower with a 6.2 ± 8.9 % and 56.6 ± 4.5 % release compared to 60.9 ± 14.6 % and 76.8 ± 19.7 % release from free DOX loaded hydrogel since DOX release was controlled by PCL microspheres. When interacted with human breast cancer cell line (MCF-7), DOX-PCL-MSs were able to disrupt cell and spheroid morphology after 7 days at concentrations as low as 12 μg/mL loaded DOX. In vitro cytotoxicity study has showed that, DOX-PCL-MSs loaded hydrogel was able to decrease MCF-7 viability after 7 days of incubation with controlled release of DOX. While free DOX releasing hydrogel has lost cytotoxic activity even after 4 days of incubation. Furthermore, ability of PVA/PUL hydrogel to support L929 cell attachment was shown in the study, suggesting hydrogels potential for promoting tissue regeneration after anti-cancer treatment. The study reveals that PVA/PUL hybrid hydrogels loaded with DOX-PCL-MSs has impactful potential in post-surgical treatment of breast cancer.

A Bacterial Responsive Microneedle Dressing with Hydrogel Backing Layer for Chronic Wound Treatment.

The treatment of chronic wounds still presents great challenges due to being infected by biofilms and the damaged healing process. The current treatments do not address the needs of chronic wounds. In this study, a highly effective dressing (Dox-DFO@MN Hy) for the treatment of chronic wounds is described. This dressing combines the advantages of microneedles (MNs) and hydrogels in the treatment of chronic wounds. MNs is employed to debride the biofilms and break down the wound barrier, providing rapid access to therapeutic drugs from hydrogel backing layer. Importantly, to kill the pathogenic bacteria in the biofilms specifically, Doxycycline hydrochloride (Dox)is wrapped into the polycaprolactone (PCL) microspheres that have lipase-responsive properties and loaded into the tips of MNs. At the same time, hydrogel backing layer is used to seal the wound and accelerate wound healing. Benefiting from the combination of two advantages of MNs and hydrogel, the dressing significantly reduces the bacteria in the biofilms and effectively promotes angiogenesis and cell migration in vitro. Overall, Dox-DFO@MN Hy can effectively treat chronic wounds infected with biofilms, providing a new idea for the treatment of chronic wounds.

Nanofibrous Dressing with Nanocomposite Monoporous Microspheres for Chemodynamic Antibacterial Therapy and Wound Healing.

The excessive use of antibiotics and consequent bacterial resistance have emerged as crucial public safety challenges for humanity. As a promising antibacterial treatment, using reactive oxygen species (ROS) can effectively address this problem and has the advantages of being highly efficient and having low toxicity. Herein, electrospinning and electrospraying were employed to fabricate magnesium oxide (MgO)-based nanoparticle composited polycaprolactone (PCL) nanofibrous dressings for the chemodynamic treatment of bacteria-infected wounds. By utilizing electrospraying, erythrocyte-like monoporous PCL microspheres incorporating silver (Ag)- and copper (Cu)-doped MgO nanoparticles were generated, and the unique microsphere-filament structure enabled efficient anchoring on nanofibers. The composite dressings produced high levels of ROS, as confirmed by the 2,7-dichloriflurescin fluorescent probe. The sustained generation of ROS resulted in efficient glutathione oxidation and a remarkable bacterial killing rate of approximately 99% against Staphylococcus aureus (S. aureus). These dressings were found to be effective at treating externally infected wounds. The unique properties of these composite nanofibrous dressings suggest great potential for their use in the medical treatment of bacteria-infected injuries.

Electrosprayed low toxicity polycaprolactone microspheres from low concentration solutions

Abstract This work describes the successful tunable production of polycaprolactone (PCL) microspheres using very low-concentration solutions. The PCL solutions (1, 3, and 5 w/v%) were prepared with different solvents (dichloromethane (DCM) and chloroform (CHL)) and electrosprayed at different distances (5, 10, and 15 cm). The solubility and viscosity of PCL solutions were in accordance with the polymer concentrations, demonstrating PCL-DCM gave a higher solubility of PCL, but PCL-CHL solutions had a higher viscosity. Optical microscopy (OM) and field emission-scanning electron microscopy (FE-SEM) revealed that the PCL-DCM preparations produced a smaller and more uniform microsphere size and pore size compared to PCL-CHL microspheres. The linear regression analysis showed that the solubility and viscosity of PCL concentration influence the size of microspheres more greatly than the pore size. The toxicity results indicated that PCL-CHL and PCL-DCM are well-tolerated by zebrafish embryos that were able to follow a normal growth pathway and can thus be deemed safe.

Evaluation of the self-healing capabilities and resistance to thermal cycling of a shape-memory epoxy coating containing polycaprolactone microspheres

The aim of this work was to prepare a shape-memory epoxy coating containing polycaprolactone microspheres (SMEP-PCL) and study its resistance to thermal cycling, which is yet to be evaluated in coatings prepared with similar approaches, as well as further characterize its self-healing capabilities. Firstly, the prepared microspheres were characterized by scanning electron microscopy (SEM) and laser diffraction. Afterwards, the dispersion of the PCL microspheres in the coating was examined and experiments were conducted with differential scanning calorimetry (DSC) and Fourier-transform infrared spectroscopy (FTIR) to determine the glass transition temperature and investigate the curing reaction of the prepared coating, respectively. Then, the healing promoted by the reversible plasticity and the melt of the polycaprolactone microspheres mechanisms were studied by SEM, Raman Imaging, electrochemical impedance spectroscopy (EIS) and scanning vibrating electrode technique (SVET). Finally, thermal cycling tests were conducted and the samples were later visually evaluated for thermal stress damage and by EIS and pull-off adhesion strength tests. The SMEP-PCL of the present work was able to reproduce the self-healing results obtained from previous reports, even improving upon the self-healing efficiency obtained in other studies, in the SVET experiment. The results of the EIS measurements after the thermal cycles, pointed out to a minor reduction on the barrier properties of the SMEP and SMEP-PCL, which should be further investigated. Nonetheless, the adherence of both coatings was unhindered by the thermal cycles, which is a highly positive result for the future application of coatings based on this approach. Also, the SMEP-PCL exhibited substantially higher average values of adhesion strength compared to the SMEP, showing that the addition of PCL microspheres significantly improved the adherence of the coating and signaling great compatibility between them. This work also underlines how the healing efficiency of coatings with this approach are highly dependent on the type and extension of damage, as the healing observed in the two types of damage studied were exceedingly different.

Development of In Situ Microfluidic System for Preparation of Controlled Porous Microsphere for Tissue Engineering.

In this study, we present an in situ microfluidic system to precisely control highly porous polycaprolactone microspheres as tissue templates for tissue engineering. The porosity of the microspheres was controlled by adjusting the flow rates of the polymer phase and the pore-generating material phase in the dispersed phase. The microfluidic flow-focusing technique was adopted to manufacture porous microspheres using a relatively highly viscous polymer solution, and the device was fabricated by conventional photolithography and PDMS casting. The fabricated in situ microfluidic system was used to precisely control the pore size of monodispersed polycaprolactone microspheres. The porous microspheres with controlled pore sizes were evaluated by culturing HDF cells on the surface of porous microspheres and injection into the subcutaneous tissue of rats. We found that the increased pore size of the microspheres improved the initial proliferation rate of HDF cells after seeding and relieved the inflammatory response after the implantation of porous microspheres in the subcutaneous tissue of rats.

Integration of micro-CT and histology data for vasculature morpho-functional analysis in tissue regeneration

The demand for artificial or bioartificial engineered tissues is increasing today in regenerative medicine techniques to replace and restore the physiological function of damaged tissues. Such engineered constructs hold different properties depending on the tissue to be replicated. As for vascularized tissues, complex biocompatible structures, namely scaffolds, play a key role in supporting oxygen and nutrient supply, thus sustaining tissue neoformation and integration with the host. Scaffold architecture significantly impacts its regenerative potential, while preclinical trials are essential to define scaffold-host interactions. In compliance with the 3 R principle, there is a clear need to optimize both the procedures to evaluate scaffold performance and the analysis methodology decreasing the number of animals required to gain consistent data. In parallel, current technologies used in preclinical research generate huge amounts of data that need to be elaborated and interpreted correctly. Therefore, we designed this study to evaluate the results of scaffold integration with the host tissue after implantation in a mouse subcutaneous pocket model. We evaluated the angiogenic response developed by the host and the degree of scaffold integration by using a combined morphometric approach based on both histological and micro-CT analyses. Six-layer scaffolds, made of polycaprolactone (PCL) microspheres, with an ordered structure were produced by thermal sintering. Scaffolds were then implanted in BALB/c mice and retrieved 21 days post-implantation when the animals were deeply anesthetized and perfused with Microfil, a contrast agent for micro-CT. Here, we describe a method to extract quantitative data from micro-CT reconstructions such as (i) total vessel volume; (ii)% of vessel penetration; (iii) distribution of vessel diameters. The general principle of this approach is the refinement of the region of interest (ROI), thus producing a volume of interest (VOI) that matches scaffold volume. This VOI serves as a dataset from which to extract volumetric information. Then VOIs are divided into three identical parts, proximal, median, and distal, to follow the vessel progression into the scaffold, thus obtaining their depth of penetration (DoP). By this methodology, we observed in mean, among the analyzed samples, a vessel invasion for 1,38 mm3 corresponding to the 1,53% of the scaffold volume. We then looked at the diameter distribution being this value a key indicator of vessel maturity, highlighting that 55% of vessels fall into the range from 5,99–53.99 µm while the remaining 45% are distributed into intervals from 54 to 136 µm. In parallel, to evaluate tissue integration in detail, histological and immunofluorescent analyses were performed to look at vessel distribution and collagen synthesis. Histological results strongly correlate with the micro-CT data providing, however, an overview of the ingrowth tissues. In addition, by immunofluorescent analysis we demonstrate that newly formed vessels are mature at the considered time point and tissue collagen deposition is widespread within the scaffolds. Collectively, we propose a new method to track vessel formation by using a multi-modal approach posing the basis for: i) the fabrication of novel scaffolds for Tissue Engineering; ii) the integration of detailed information for a wide range of morphological and functional analyses.

Magnetic polycaprolactone microspheres: drug encapsulation and control

Targeted drug delivery (TDD) systems have several advantages, especially with drugs having toxic side effects such as lornoxicam (LX) which shows high hepatotoxicity and nephrotoxicity, especially with long-term use. This work represents an attempt to control magnetic microspheres encapsulating LX and magnetite nanoparticles (MNPs) for potential targeted drug delivery of LX. Superparamagnetic nanoparticles were fabricated via the co-precipitation method and together with LX were encapsulated into polycaprolactone (PCL) microspheres through an oil-in-water (O/W) emulsion solvent evaporation method. The effects of changing the amount of drug, MNPs, and volume of the aqueous phase were investigated by preparing several microsphere formulations. Increasing the amount of encapsulated MNPs increased the magnetization of the microspheres without affecting the morphology. Doubling the volume of the aqueous phase resulted in a higher encapsulation efficiency and drug loading; 83.9% and 10.7%, respectively, while increasing the amount of drug had a negative effect on both drug loading and encapsulation efficiency. Drug release from the microspheres was successfully achieved and showed a biphasic nature. A system of four planar coils was then used to magnetically control the movement of a cluster of capsules in a glycerin medium, as a simulation for the targeting process. The microspheres were successfully controlled to move in a U-turn path with sharp corners demonstrating their potential for TDD applications.

Computer-aided patterning of PCL microspheres to build modular scaffolds featuring improved strength and neovascularized tissue integration

In the past decade, modular scaffolds prepared by assembling biocompatible and biodegradable building blocks (e.g. microspheres) have found promising applications in tissue engineering (TE) towards the repair/regeneration of damaged and impaired tissues. Nevertheless, to date this approach has failed to be transferred to the clinic due to technological limitations regarding microspheres patterning, a crucial issue for the control of scaffold strength, vascularization and integration in vivo. In this work, we propose a robust and reliable approach to address this issue through the fabrication of polycaprolactone (PCL) microsphere-based scaffolds with in-silico designed microarchitectures and high compression moduli. The scaffold fabrication technique consists of four main steps, starting with the manufacture of uniform PCL microspheres by fluidic emulsion technique. In the second step, patterned polydimethylsiloxane (PDMS) moulds were prepared by soft lithography. Then, layers of 500 µm PCL microspheres with geometrically inspired patterns were obtained by casting the microspheres onto PDMS moulds followed by their thermal sintering. Finally, three-dimensional porous scaffolds were built by the alignment, stacking and sintering of multiple (up to six) layers. The so prepared scaffolds showed excellent morphological and microstructural fidelity with respect to the in-silico models, and mechanical compression properties suitable for load bearing TE applications. Designed porosity and pore size features enabled in vitro human endothelial cells adhesion and growth as well as tissue integration and blood vessels invasion in vivo. Our results highlighted the strong impact of spatial patterning of microspheres on modular scaffolds response, and pay the way about the possibility to fabricate in silico-designed structures featuring biomimetic composition and architectures for specific TE purposes.

Dual sustained-release PTMC/PCL porous microspheres for lipid-soluble drugs

It is still a considerable research challenge to design biodegradable drug delivery systems that efficiently transport lipid-soluble drugs with controlled release. In the present study, a microsphere delivery system, γ-cyclodextrin (γ-CD)/glutathione (GSH)-atorvastatin (AT) fibrous nanoparticles (γ-CD/GSH-AT FNs) loaded polytrimethylene carbonate (PTMC)/polycaprolactone (PCL) microspheres (PTMC/PCL/γ-CD/GSH-AT MPs), was constructed through an exquisite method. The results show that a large number of γ-CD/GSH-AT FNs can be encapsulated during the formation of microspheres and released in a controllable manner. Notably, the high dispersibility and drug loading of FNs can load with lipid-soluble drugs and protect the drugs from the solvent during microsphere preparation. FNs and MPs can achieve dual release. First, with the degradation of the microspheres, the encapsulated FNs were gradually released into the local microenvironment. Subsequently, the FNs began to dissolve and release the loaded AT over a period of more than 3 days. Therefore, the dual sustained-release drug delivery system can maintain the blood drug concentration for a longer time and reduce the number of administrations and the side effects of the drug. This study provides new ideas for the on-demand manufacture of controllable degradable drug delivery platforms to treat diseases.

Novel Utilization of Therapeutic Coatings Based on Infiltrated Encapsulated Rose Bengal Microspheres in Porous Titanium for Implant Applications.

Despite the increasing progress achieved in the last 20 years in both the fabrication of porous dental implants and the development of new biopolymers for targeting drug therapy, there are important issues such as bone resorption, poor osseointegration, and bacterial infections that remain as critical challenges to avoid clinical failure problems. In this work, we present a novel microtechnology based on polycaprolactone microspheres that can adhere to porous titanium implant models obtained by the spacer holder technique to allow a custom biomechanical and biofunctional balance. For this purpose, a double emulsion solvent evaporation technique was successfully employed for the fabrication of the microparticles properly loaded with the antibacterial therapeutic agent, rose bengal. The resulting microspheres were infiltrated into porous titanium substrate and sintered at 60 °C for 1 h, obtaining a convenient prophylactic network. In fact, the sintered polymeric microparticles were demonstrated to be key to controlling the drug dissolution rate and favoring the early healing process as consequence of a better wettability of the porous titanium substrate to promote calcium phosphate nucleation. Thus, this joint technology proposes a suitable prophylactic tool to prevent both early-stage infection and late-stage osseointegration problems.

One-step preparation of hydroxyapatite-loaded magnetic Polycaprolactone hollow microspheres for malachite green adsorption by Pickering emulsion template method

In this study, hydroxyapatite (HAp) nanorods were prepared by a simple hydrothermal method and hydrophobically modified with lauric acid (LA). Modified HAp and magnetic triiron tetraoxide (Fe3O4) nanoparticles as emulsifiers were loaded on polycaprolactone (PCL) microspheres by Pickering emulsion template method. The structure, composition and morphology of prepared HAp and m-RHAp-PCL microspheres were characterized by IR, XRD, SEM and TGA. Furthermore, the adsorption capacity of pure HAp and m-RHAp-PCL microspheres was investigated by malachite green (MG) as a model dye. The results showed that the adsorption processes of pure HAp and m-RHAp-PCL microspheres correlated better with the Langmuir isothermal adsorption curve. The maximum adsorption capacity of m-RHAp-PCL microspheres was 609 mg/g, and the relative adsorption capacity of HAp on microspheres was higher than that of pure HAp, indicating its greater adsorption potential for MG. The values of RL and 1/n indicated that the adsorption process was spontaneous. The adsorption kinetic data of samples was in good agreement with the pseudo-second-order kinetic model. In addition, the adsorbent could be easily recovered under magnetic fields. The removal ability of MG was retained after four cycles, which demonstrated the excellent reusability and stability of m-RHAp-PCL microspheres for MG adsorption from aqueous as a potential adsorbent candidate material.

Integrated polycaprolactone microsphere-based scaffolds with biomimetic hierarchy and tunable vascularization for osteochondral repair

Osteochondral lesion potentially causes a variety of joint degenerative diseases if it cannot be treated effectively and timely. Microfracture as the conservative surgical choice achieves limited results for the larger defect whereas cartilage patches trigger integrated instability and cartilage fibrosis. To tackle aforementioned issues, here we explore to fabricate an integrated osteochondral scaffold for synergetic regeneration of cartilage and subchondral bone in one system. On the macro level, we fabricated three integrated scaffolds with distinct channel patterns of Non-channel, Consecutive-channel and Inconsecutive-channel via Selective Laser Sintering (SLS). On the micro level, both cartilage zone and subchondral bone zone of integrated scaffold were made of small polycaprolactone (PCL) microspheres and large PCL microspheres, respectively. Our findings showed that Inconsecutive-channel scaffolds possessed integrated hierarchical structure, adaptable compression strength, gradient interconnected porosity. Cartilage zone presented a dense phase for the inhibition of vessel invasion while subchondral bone zone generated a porous phase for the ingrowth of bone and vessel. Both cartilage regeneration and subchondral bone remodeling in the group of Inconsecutive-channel scaffolds have been demonstrated by histological evaluation and immunofluorescence staining in vivo. Consequently, our current work not only achieves an effective and regenerative microsphere scaffold for osteochondral reconstruction, but also provides a feasible methodology to recover injured joint through integrated design with diverse hierarchy. Statement of significanceRecovery of osteochondral lesion highly depends on hierarchical architecture and tunable vascularization in distinct zones. We therefore design a special integrated osteochondral scaffold with inconsecutive channel structure and vascularized modulation. The channel pattern impacts on mechanical strength and the infiltration of bone marrow, and eventually triggers synergetic repair of osteochondral defect. The cartilage zone of integrated scaffolds consisted of small PCL microspheres forms a dense phase for physical restriction of vascularized infiltration whereas the subchondral bone zone made of large PCL microspheres generates porous trabecula-like structure for promoting vascularization. Consequently, the current work indicates both mechanical adaptation and regional vascularized modulation play a pivotal role on osteochondral repair.

Improving motor neuron-like cell differentiation of hEnSCs by the combination of epothilone B loaded PCL microspheres in optimized 3D collagen hydrogel

Spinal cord regeneration is limited due to various obstacles and complex pathophysiological events after injury. Combination therapy is one approach that recently garnered attention for spinal cord injury (SCI) recovery. A composite of three-dimensional (3D) collagen hydrogel containing epothilone B (EpoB)-loaded polycaprolactone (PCL) microspheres (2.5 ng/mg, 10 ng/mg, and 40 ng/mg EpoB/PCL) were fabricated and optimized to improve motor neuron (MN) differentiation efficacy of human endometrial stem cells (hEnSCs). The microspheres were characterized using liquid chromatography-mass/mass spectrometry (LC-mas/mas) to assess the drug release and scanning electron microscope (SEM) for morphological assessment. hEnSCs were isolated, then characterized by flow cytometry, and seeded on the optimized 3D composite. Based on cell morphology and proliferation, cross-linked collagen hydrogels with and without 2.5 ng/mg EpoB loaded PCL microspheres were selected as the optimized formulations to compare the effect of EpoB release on MN differentiation. After differentiation, the expression of MN markers was estimated by real-time PCR and immunofluorescence (IF). The collagen hydrogel containing the EpoB group had the highest HB9 and ISL-1 expression and the longest neurite elongation. Providing a 3D permissive environment with EpoB, significantly improves MN-like cell differentiation and maturation of hEnSCs and is a promising approach to replace lost neurons after SCI.

Integrated Osteochondral Microsphere Scaffolds with Biomimetic Architecture and Regional Vascularization for Joint Repair

Osteochondral lesion potentially causes a variety of joint degenerative diseases if it cannot be treated effectively and timely. Microfracture as the first line surgical choice achieves limited results for the larger defect whereas cartilage patches trigger integrated instability and cartilage fibrosis. To tackle aforementioned issues, here we explore to construct an integrated osteochondral scaffold for synergetic regeneration of cartilage and subchondral bone in one system. On the macro level, we fabricated three integrated scaffolds with distinct channel structure of Non-channel, Consecutive-channel and Inconsecutive-channel via Selective Laser Sintering (SLS). On the micro level, cartilage zone and subchondral bone zone of integrated scaffold consisted of small polycaprolactone (PCL) microspheres with the diameter of 50 μm and large PCL microspheres with the diameter of 150 μm, respectively. As a result, cartilage zone exhibited a dense phase for the inhibition of vessel invasion while subchondral zone generated a porous phase for the ingrowth of bone and vessel. Our findings showed that Inconsecutive-channel scaffolds possessed biomimetic hierarchical structure, adequate mechanical properties, gradient interconnected porosity in comparison with Non-channel and Consecutive-channel groups. Moreover, Inconsecutive-channel scaffolds obviously induced cartilage regeneration and subchondral bone remodeling. Consequently, this work not only achieves an effective and regeneratable microsphere scaffold for osteochondral reconstruction, but also provides a feasible methodology to recover injured joint through integrated design pattern. Funding Information: This work was financially supported by the National Key Research and Development Program of China (2017YFC1103900), the National Natural Science Foundation of China (32171323, 91939111), Key Research and Development Program of Hubei Province (2020BCB056), International Science and Technology Cooperation Projects of Shenzhen (GJHZ20200731095211035), Sanming Project of Medicine in Shenzhen (SZSM201812055), and the Fundamental Research Funds for the Central Universities (2019kfyRCPY103). Declaration of Interests: The authors declare no conflict of interest. Ethics Approval Statement: All procedures for animal experiments were approved by the Institutional Animal Care and Use Committee of Huazhong University of Science and Technology (SYXK20170094).

Central composite design optimization for a controlled valsartan release from polycaprolactone microspheres

AbstractThis investigation aimed to develop polycaprolactone (PCL) microspheres, which provide better control of valsartan release. Central composite experimental design (2‐factor, 3‐level) was used to study the effect of two independent variables, namely drug amount (X1) and organic phase volume (X2), on encapsulation efficiency (Y1) and particle size (Y2). The drug‐containing microspheres were prepared by a single emulsion solvent evaporation method and characterized by various techniques including high performance liquid chromatography, thermal analysis, X‐ray diffraction analysis, scanning electron microscopy, and particle size analysis. The optimum conditions found by the quadratic models were yielded microspheres with an encapsulation efficiency of about 79% and a particle size of 51 μm. The optimal formulation improved drug release in simulated gastric fluid for the first 2 h, while it provided a sustained release, in phosphate buffered saline (pH 6.8). The formulations prepared with a lower organic phase volume (4 ml) have reduced the burst effect and therefore provided better control of valsartan release. Mathematical modeling studies showed that the encapsulated drug release was governed by Fickian‐diffusion mechanism.

Comparative Evaluation of Physical Characteristics and Preclinical Data of a Novel Monodisperse Polycaprolactone Microspheres Filler

Demand for dermal fillers has been increasing gradually over the past decade. Polycaprolactone (PCL) fillers, a biodegradable polymer, not only naturally maintain the volume of the skin, but also stimulate collagen production by microsphere. However, inflammation can be caused by several factors such as large diameters, non-uniformity, uneven surfaces and non-spherical shapes of microspheres in use. Thus, a filler using microspheres with a uniform diameter of more than 20μm and spherical shape was developed. The main purpose of this study was to evaluate the efficacy and safety of newly monodisperse polycaprolactone microspheres fillers, IVL-F001 with smaller microsphere size and better morphology against a conventional commercial PCL filler. The morphology and diameters of microsphere included in IVL-F001 and the PCL filler were analyzed, and the viscoelasticity and inject ability of both fillers were examined. After intradermal injection to hairless mice, the durability and efficacy of both fillers were evaluated through PRIMOSLITE and Folliscope for 24 weeks. Histology was performed to assess the biocompatibility, inflammation, and collagen synthesis. Microspheres of IVL-F001 demonstrated a narrow size distribution with average diameter of 34.16μm and distribution of 4.11. The level of injection force was low and the elasticity (G') was high compared to the licensed PCL filler. In the histopathological evaluation, IVL-F001 had significantly lower inflammatory reactions and higher collagen synthesis compared to the licensed PCL filler. These data indicated that IVL-F001 has lower inflammatory reaction and improved persistence compared with commercial PCL filler. This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266.