Pendant small functional groups on poly(ϵ-caprolactone) substrate modulate adhesion, proliferation and differentiation of human mesenchymal stem cells

The role of plasma-induced surface chemistry on polycaprolactone nanofibers to direct chondrogenic differentiation of human mesenchymal stem cells

Bone marrow-derived mesenchymal stromal cells (BMSCs) are extensively being utilized for cartilage regeneration owing to their excellent differentiation potential and availability. However, controlled differentiation of BMSCs towards cartilaginous phenotypes to heal full-thickness cartilage defects remains challenging. This study investigates how different surface properties induced by either coating deposition or biomolecules immobilization onto nanofibers (NFs) could affect BMSCs chondro-inductive behavior. Accordingly, electrospun poly(ε-caprolactone) (PCL) NFs were exposed to two surface modification strategies based on medium-pressure plasma technology. The first strategy is plasma polymerization, in which cyclopropylamine (CPA) or acrylic acid (AcAc) monomers were plasma polymerized to obtain amine- or carboxylic acid-rich NFs, respectively. The second strategy uses a combination of CPA plasma polymerization and a post-chemical technique to immobilize chondroitin sulfate (CS) onto the NFs. These modifications could affect surface roughness, hydrophilicity, and chemical composition while preserving the NFs' nano-morphology. The results of long-term BMSCs culture in both basic and chondrogenic media proved that the surface modifications modulated BMSCs chondrogenic differentiation. Indeed, the incorporation of polar groups by different modification strategies had a positive impact on the cell proliferation rate, production of the glycosaminoglycan matrix, and expression of extracellular matrix proteins (collagen I and collagen II). The chondro-inductive behavior of the samples was highly dependent on the nature of the introduced polar functional groups. Among all samples, carboxylic acid-rich NFs promoted chondrogenesis by higher expression of aggrecan, Sox9, and collagen II with downregulation of hypertrophic markers. Hence, this approach showed an intrinsic potential to have a non-hypertrophic chondrogenic cell phenotype.

Highly resilient and fatigue-resistant poly(4-methyl-ε-caprolactone) porous scaffold fabricated via thiol-yne photo-crosslinking/salt-templating for soft tissue regeneration

Elastomeric scaffolds, individually customized to mimic the structural and mechanical properties of natural tissues have been used for tissue regeneration. In this regard, polyester elastic scaffolds with tunable mechanical properties and exceptional biological properties have been reported to provide mechanical support and structural integrity for tissue repair. Herein, poly(4-methyl-ε-caprolactone) (PMCL) was first double-terminated by alkynylation (PMCL-DY) as a liquid precursor at room temperature. Subsequently, three-dimensional porous scaffolds with custom shapes were fabricated from PMCL-DY via thiol-yne photocrosslinking using a practical salt template method. By manipulating the M_n of the precursor, the modulus of compression of the scaffold was easily adjusted. As evidenced by the complete recovery from 90% compression, the rapid recovery rate of >500 mm min^-1, the extremely low energy loss coefficient of <0.1, and the superior fatigue resistance, the PMCL20-DY porous scaffold was confirmed to harbor excellent elastic properties. In addition, the high resilience of the scaffold was confirmed to endow it with a minimally invasive application potential. In vitro testing revealed that the 3D porous scaffold was biocompatible with rat bone marrow stromal cells (BMSCs), inducing BMSCs to differentiate into chondrogenic cells. In addition, the elastic porous scaffold demonstrated good regenerative efficiency in a 12-week rabbit cartilage defect model. Thus, the novel polyester scaffold with adaptable mechanical properties may have extensive applications in soft tissue regeneration.

Surface modifications of biomaterials in different applied fields

Biomaterial implantation into the human body plays a key role in the medical field and biological applications. Increasing the life expectancy of biomaterial implants, reducing the rejection reaction inside the human body and reducing the risk of infection are the problems in this field that need to be solved urgently. The surface modification of biomaterials can change the original physical, chemical and biological properties and improve the function of materials. This review focuses on the application of surface modification techniques in various fields of biomaterials reported in the past few years. The surface modification techniques include film and coating synthesis, covalent grafting, self-assembled monolayers (SAMs), plasma surface modification and other strategies. First, a brief introduction to these surface modification techniques for biomaterials is given. Subsequently, the review focuses on how these techniques change the properties of biomaterials, and evaluates the effects of modification on the cytocompatibility, antibacterial, antifouling and surface hydrophobic properties of biomaterials. In addition, the implications for the design of biomaterials with different functions are discussed. Finally, based on this review, it is expected that the biomaterials have development prospects in the medical field.

Tuning Cell Behavior on 3D Scaffolds Fabricated by Atmospheric Plasma-Assisted Additive Manufacturing

Three-dimensional (3D) scaffolds with optimum physicochemical properties are able to elicit specific cellular behaviors and guide tissue formation. However, cell-material interactions are limited in scaffolds fabricated by melt extrusion additive manufacturing (ME-AM) of synthetic polymers, and plasma treatment can be used to render the surface of the scaffolds more cell adhesive. In this study, a hybrid AM technology, which combines a ME-AM technique with an atmospheric pressure plasma jet, was employed to fabricate and plasma treat scaffolds in a single process. The organosilane monomer (3-aminopropyl)trimethoxysilane (APTMS) and a mixture of maleic anhydride and vinyltrimethoxysilane (MA-VTMOS) were used for the first time to plasma treat 3D scaffolds. APTMS treatment deposited plasma-polymerized films containing positively charged amine functional groups, while MA-VTMOS introduced negatively charged carboxyl groups on the 3D scaffolds' surface. Argon plasma activation was used as a control. All plasma treatments increased the surface wettability and protein adsorption to the surface of the scaffolds and improved cell distribution and proliferation. Notably, APTMS-treated scaffolds also allowed cell attachment by electrostatic interactions in the absence of serum. Interestingly, cell attachment and proliferation were not significantly affected by plasma treatment-induced aging. Also, while no significant differences were observed between plasma treatments in terms of gene expression, human mesenchymal stromal cells (hMSCs) could undergo osteogenic differentiation on aged scaffolds. This is probably because osteogenic differentiation is rather dependent on initial cell confluency and surface chemistry might play a secondary role.

In situ ornamenting poly(ε-caprolactone) electrospun fibers with different fiber diameters using chondrocyte-derived extracellular matrix for chondrogenesis of mesenchymal stem cells

Biomimetic instructive tissue engineering scaffolds are critical for achieving successful tissue regeneration. In the present study, we developed a novel scaffold via ornamenting poly(ε-caprolactone) (PCL) electrospun fibers with a chondrocyte-derived extracellular matrix (ECM)-coating, which was applied for chondrogenesis of mesenchymal stem cells (MSCs). PCL fibrous films with different fiber diameters (1282±121 nm, 549±61 nm and 285±38 nm) were first prepared via electrospinning. Rabbit articular chondrocytes (rACs) were cultured on PCL fibrous scaffolds, followed by a decellularization treatment to generate decellularized ECM (dECM)-coated PCL scaffolds (dECM/PCL). Rabbit bone marrow-derived MSCs (rMSCs) were then seeded onto these scaffolds and adhesion, proliferation and chondrogenic differentiation were evaluated. dECM/PCL scaffolds displayed distinct surface microstructural features with varying fiber diameters and fibrous mesh-like ECM with more developed collagen fibers was observed on nanofibers. On dECM/PCL scaffolds, rMSCs tended to spread more at 24 h post-seeding and proliferated better within 7 d compared to those on uncoated PCL scaffolds. Based on analysis of gene expression, rMSCs underwent the best chondrogenic differentiation on dECM/PCL scaffolds of 549-nm fibers. Collectively, such dECM/PCL composite scaffolds are very promising for cartilage tissue regeneration.

Osteochondral Regeneration Using Adipose Tissue-Derived Mesenchymal Stem Cells

Osteoarthritis (OA) is a major joint disease that promotes locomotor deficiency during the middle- to old-age, with the associated disability potentially decreasing quality of life. Recently, surgical strategies to reconstruct both articular cartilage and subchondral bone for OA have been diligently investigated for restoring joint structure and function. Adipose tissue-derived mesenchymal stem cells (AT-MSCs), which maintain pluripotency and self-proliferation ability, have recently received attention as a useful tool to regenerate osteocartilage for OA. In this review, several studies were described related to AT-MSC spheroids, with scaffold and scaffold-free three-dimensional (3D) constructs produced using “mold” or “Kenzan” methods for osteochondral regeneration. First, several examples of articular cartilage regeneration using AT-MSCs were introduced. Second, studies of osteochondral regeneration (not only cartilage but also subchondral bone) using AT-MSCs were described. Third, examples were presented wherein spheroids were produced using AT-MSCs for cartilage regeneration. Fourth, osteochondral regeneration following autologous implantation of AT-MSC scaffold-free 3D constructs, fabricated using the “mold” or “Kenzan” method, was considered. Finally, prospects of osteochondral regeneration by scaffold-free 3D constructs using AT-MSC spheroids were discussed.

Fabrication and evaluation of modified poly(ethylene terephthalate) microfibrous scaffolds for hepatocyte growth and functionality maintenance

For hepatocyte culture in vitro, the surface feature of utilized scaffolds exerts a direct impact on cell adhesion, growth and differentiated functionality. Herein, to regulate hepatocyte growth and differentiated functionality, modified microfibrous scaffolds were fabricated by surface grafting monoamine terminated lactobionic lactone (L-NH₂) and gelatin onto non-woven poly(ethylene terephthalate) (PET) fibrous substrate (PET-Gal and PET-Gel), respectively. The physicochemical properties of PET scaffolds before and after modification were characterized. Upon 15-day culture, the effects of modified PET scaffolds on growth and differentiated functionality of human induced hepatocytes (hiHeps) were evaluated, compared with that of control without modification. Results demonstrated that both L-NH₂ and gelatin modifications improved scaffold properties including hydrophilicity, water uptake ratio, stiffness and roughness, resulting in efficient cell adhesion, ~20-fold cell expansion and enhanced differentiated functionality. After culture for 15 days, PET-Gal cultured cells formed aggregates, displaying better cell viability and significantly higher differentiated functionality regarding albumin secretion, urea synthesis, phases I (cytochrome P450, CYP1A1/2 and CYP3A4) and II (uridine 5'-diphosphate glucuronosyltransferases, UGT) enzyme activity, biliary excretion and detoxification ability (ammonia elimination and bilirubin conjugation), compared with PET and PET-Gel cultured ones. Hence, as a three-dimensional (3D) microfibrous scaffold, PET-Gal promotes hiHeps growth and differentiated functionality maintenance, which is promisingly utilized in bioartificial liver (BAL) bioreactors.

In vitro and preclinical characterisation of compressed, macro-porous and collagen coated poly-ε-caprolactone electro-spun scaffolds

Low in macro-porosity electro-spun scaffolds are often associated with foreign body response, whilst macro-porous electro-spun scaffolds have low mechanical integrity. Herein, compressed, macro-porous and collagen (bovine Achilles tendon and human recombinant) coated electro-spun poly-ε-caprolactone scaffolds were developed and their biomechanical, in vitro and in vivo properties were assessed. Collagen coating, independently of the source, did not significantly affect the biomechanical properties of the scaffolds. Although no significant difference in cell viability was observed between the groups, collagen coated scaffolds induced significantly higher DNA concentration. In vivo, no signs of adverse tissue effect were observed in any of the groups and all groups appeared to equally integrate into the subcutaneous tissue. It is evidenced that macro-porous poly-ε-caprolactone electro-spun meshes with adequate mechanical properties and acceptable host response can be developed for biomedical applications.

Structurally Tunable Reduced Graphene Oxide Substrate Maintains Mouse Embryonic Stem Cell Pluripotency

Culturing embryonic stem cells (ESCs) in vitro usually requires animal-derived trophoblast cells, which may cause pathogenic and immune reactions; moreover, the poor repeatability between batches hinders the clinical application of ESCs. Therefore, it is essential to synthesize a xenogeneic-free and chemically well-defined biomaterial substrate for maintaining ESC pluripotency. Herein, the effects of structurally tunable reduced graphene oxide (RGO) substrates with different physicochemical properties on ESC pluripotency are studied. Colony formation and CCK-8 assays show that the RGO substrate with an average 30 µm pore size promotes cell survival and proliferation. The unannealed RGO substrate promotes ESC proliferation significantly better than the annealed substrate due to the interfacial hydrophilic groups. The RGO substrate can also maintain ESC for a long time. Additionally, immunofluorescence staining shows that ESCs cultured on an RGO substrate highly express E-cadherin and β-catenin, whereas after being modified by Dickkopf-related protein 1, the RGO substrate is unable to sustain ESC pluripotency. Furthermore, the cell line that interferes with E-cadherin is also unable to maintain pluripotency. These results confirm that the RGO substrate maintains ESC pluripotency by promoting E-cadherin-mediated cell-cell interaction and Wnt signaling.

The optimization and production of stable homogeneous amine enriched surfaces with characterized nanotopographical properties for enhanced osteoinduction of mesenchymal stem cells

Silane modification has been proposed as a powerful biomaterial surface modification tool. This is the first comprehensive investigation into the effect of silane chain length on the resultant properties of -NH₂ silane monolayers and the associated osteoinductive properties of the surface. A range of -NH₂ presenting silanes, chain length 3-11, were introduced to glass coverslips and characterized using water contact angles, atomic force microscopy, X-ray photoelectron spectroscopy, and Ninhydrin assays. The ability of the variation in chain length to form a homogenous layer across the entirety of the surfaces was also assessed. The osteoinductive potential of the resultant surfaces was evaluated by real-time polymerase chain reaction, immunocytochemistry, and von Kossa staining. Control of surface chemistry and topography was directly associated with changes in chain length. This resulted in the identification of a specific, chain length 11 (CL11) which significantly increased the osteoinductive properties of the modified materials. Only CL11 surfaces had a highly regular nano-topography/roughness which resulted in the formation of an appetite-like layer on the surface that induced a significantly enhanced osteoinductive response (increased expression of osteocalcin, CBFA1, sclerostin, and the production of a calcified matrix) across the entirety of the surface. © 2018 The Authors Journal of Biomedical Materials Research Part A Published by Wiley Periodicals, Inc. J Biomed Mater Res Part A: 106A: 1862-1877, 2018.

PCL and PCL-based materials in biomedical applications

Biodegradable polymers have met with an increasing demand in medical usage over the last decades. One of such polymers is poly(ε-caprolactone) (PCL), which is a polyester that has been widely used in tissue engineering field for its availability, relatively inexpensive price and suitability for modification. Its chemical and biological properties, physicochemical state, degradability and mechanical strength can be adjusted, and therefore, it can be used under harsh mechanical, physical and chemical conditions without significant loss of its properties. Degradation time of PCL is quite long, thus it is used mainly in the replacement of hard tissues in the body where healing also takes an extended period of time. It is also used at load-bearing tissues of the body by enhancing its stiffness. However, due to its tailorability, use of PCL is not restricted to one type of tissue and it can be extended to engineering of soft tissues by decreasing its molecular weight and degradation time. This review outlines the basic properties of PCL, its composites, blends and copolymers. We report on various techniques for the production of different forms, and provide examples of medical applications such as tissue engineering and drug delivery systems covering the studies performed in the last decades.

Strong, Resilient, and Sustainable Aliphatic Polyester Thermoplastic Elastomers

Thermoplastic elastomers (TPEs) composed of ABA block polymers exhibit a wide variety of properties and are easily processable as they contain physical, rather than chemical, cross-links. Poly(γ-methyl-ε-caprolactone) (PγMCL) is an amorphous polymer with a low entanglement molar mass (M_e = 2.9 kg mol^-1), making it a suitable choice for tough elastomers. Incorporating PγMCL as the midblock with polylactide (PLA) end blocks (f_LA = 0.17) results in TPEs with high stresses and elongations at break (σ_B = 24 ± 2 MPa and ε_B = 1029 ± 20%, respectively) and low levels of hysteresis. The use of isotactic PLA as the end blocks (f_LLA = 0.17) increases the strength and toughness of the material (σ_B = 30 ± 4 MPa, ε_B = 988 ± 30%) due to its semicrystalline nature. This study aims to demonstrate how the outstanding properties in these sustainable materials are a result of the entanglements, glass transition temperature, segment-segment interaction parameter, and crystallinity, resulting in comparable properties to the commercially relevant styrene-based TPEs.

Free Epoxide Content Mediates Encapsulated Cell Viability and Activity through Protein Interactions in a Thermoresponsive, In Situ Forming Hydrogel

The development of synthetic and well-defined extracellular matrices that are free of xenogeneic components and are capable of inducing desired cellular responses holds great potential for use in vitro as 3D cell culture environments and in vivo as scaffolds for tissue regeneration. In this study, the impact of free and partially occupied epoxide groups on the viability, activity, and behavior of rat fibroblasts encapsulated in thermoresponsive hydrogels based on poly(N-isopropylacrylamide) (pNiPAAm) was investigated. While fibroblasts encapsulated in neat pNiPAAm remained rounded and showed significant toxicity by 5 days, those encapsulated in the epoxide-modified thermogels demonstrated not only high viability but also an ability to proliferate, attach, produce extracellular matrix (ECM) components, and cluster. The results demonstrated that the presence of free epoxide groups led to the local conjugation of available proteins to produce a modified structure in situ, which supported cell viability, activity, and cluster formation within the hydrogel.

Chemical group-dependent plasma polymerisation preferentially directs adipose stem cell differentiation towards osteogenic or chondrogenic lineages

Human adipose derived stem cells (ADSCs) are being explored for the repair of craniofacial defects due to their multi-differentiation potential and ease of isolation and expansion. Crucial to using ADSCs for craniofacial repair is the availability of materials with appropriate biomechanical properties that can support their differentiation into bone and cartilage. We tested the hypothesis that different modifications of chemical groups on the surface of a nanocomposite polymer could increase human ADSC adhesion and selectively enhance their osteogenic and chondrogenic differentiation. We show that the COOH modification significantly promoted initial cell adhesion and proliferation over 14 days compared to NH₂ surfaces. Expression of focal adhesion kinase and vinculin was enhanced after plasma surface polymerisation at 24 h. The COOH modification significantly enhanced chondrogenic differentiation as indicated by up-regulation of aggrecan and collagen II transcripts. In contrast, NH₂ group functionalised scaffolds promoted osteogenic differentiation with significantly enhanced expression of collagen I, alkaline phosphatase and osteocalcin both at the gene and protein level. Finally, chorioallantoic membrane grafting demonstrated that both NH₂ and COOH functionalised scaffolds seeded with ADSCs were biocompatible and supported vessel ingrowth apparently to a greater degree than unmodified scaffolds. In summary, our study shows the ability to direct ADSC chondrogenic and osteogenic differentiation by deposition of different chemical groups through plasma surface polymerisation. Hence this approach could be used to selectively enhance bone or cartilage formation before implantation in vivo to repair skeletal defects.

Statement of Significance

Human adipose derived stem cells (hADSCs) are an exciting stem cell source for regenerative medicine due to their plentiful supply and ease of isolation. However, the optimal environmental cues to direct stem cells towards certain lineages change have to has not been identified. We have shown that by modifying the surface of the scaffold with specific chemical groups using plasma surface polymerisation techniques we can control ADSCs differentiation. This study shows that ADSCs can be differentiated towards osteogenic and chondrogenic lineages on amine (NH₂) and carboxyl (COOH) modified scaffolds respectively. Plasma polymerisation can be easily applied to other biomaterial surfaces to direct stem cell differentiation for the regeneration of bone and cartilage.

Adhesion of mesenchymal stem cells to biomimetic polymers: A review

The mesenchymal stem cells (MSCs) are promising candidates for cell therapy due to the self-renewal, multi-potency, ethically approved state and suitability for autologous transplantation. However, key issue for isolation and manipulation of MSCs is adhesion in ex-vivo culture systems. Biomaterials engineered for mimicking natural extracellular matrix (ECM) conditions which support stem cell adhesion, proliferation and differentiation represent a main area of research in tissue engineering. Some of them successfully enhanced cells adhesion and proliferation because of their biocompatibility, biomimetic texture, and chemistry. However, it is still in its infancy, therefore intensification and optimization of in vitro, in vivo, and preclinical studies is needed to clarify efficacies as well as applicability of those bioengineered constructs. The aim of this review is to discuss mechanisms related to the in-vitro adhesion of MSCs, surfaces biochemical, biophysical, and other factors (of cell's natural and artificial micro-environment) which could affect it and a review of previous research attempting for its bio-chemo-optimization.

Poly(ε-caprolactone)-based substrates bearing pendant small chemical groups as a platform for systemic investigation of chondrogenesis

OBJECTIVES

Physiochemical properties of biomaterials play critical roles in dictating types of cell behaviour. In this study, a series of poly(ε-caprolactone) (PCL)-derived polymers bearing different small chemical groups was employed as a platform to evaluate chondrogenesis of different cell types.

MATERIALS AND METHODS

Thin films were prepared by spin-coating PCL derivatives. Rabbit articular chondrocytes (rACs) and rabbit bone marrow-derived mesenchymal stem cells (rMSCs) were seeded on to the films, and cell adhesion, proliferation, extracellular matrix production and gene expression were evaluated.

RESULTS

The presence of hydrophilic groups (-NH2 , -COOH, -OH and -C=O) promoted adhesion and proliferation of primary rACs and rMSCs. On these polymeric films, chondrogenesis of primary rACs depended on culture time. For passaged cells, re-differentiation was induced on these films by chondrogenic induction, but less for cells of passage 5 compared to passage 3. While films with hydrophilic groups favoured chondrocytic gene expression of both types of passaged cells, production of glycosaminoglycans (GAG) was similar for those of passage 3 on all films, and PCL-CH3 film better supported GAG production for cells of passage 5. Under chondrogenic conditions, rMSCs were more efficient at GAG production on PCL and PCL-NH2 films.

CONCLUSIONS

This study demonstrates that different cells displayed distinct responses to substrate surface chemistry, implying that cell-biomaterial interactions can be developmental stage dependent. This provides a novel perspective for developing biomaterials for cartilage regeneration.

Combined Chemical Groups and Topographical Nanopattern on the Poly(ε-Caprolactone) Surface for Regulating Human Foreskin Fibroblasts Behavior

Surface chemistry and substrate topography could contribute significantly to providing a biochemical and topographical cues for governing the fate of cells on the cell-material interface. However, the synergies between these two properties have not been exploited extensively for biomaterial design. Herein, we achieved spatial-controlled patterning of chemical groups on the poly(ε-caprolactone) (PCL) surface by elegant UV-nanoimprint lithography (UN-NIL). The introduction of chemical groups on the PCL surface was developed by our newly 6-benzyloxycarbonylmethyl-ε-caprolactone (BCL) monomer, which not only solved the lack of functional groups along the PCL chain but also retained the original favorable properties of PCL materials. The synergetic effect of the chemical groups and nanopatterns on the human foreskin fibroblasts (HFFs) behaviors was evaluated in detail. The results revealed that the patterned functional PCL surfaces could induce enhanced cell adhesion and proliferation, further trigger changes in HFFs morphology, orientation and collagen secretion. Taken together, this study provided a method for straightforward fabrication of reactive PCL surfaces with topographic patterns by one-step process, and they would facilitate PCL as potential candidate for cell cultivation and tissue engineering.

Silver nanoparticle based coatings enhance adipogenesis compared to osteogenesis in human mesenchymal stem cells through oxidative stress

Silver nanoparticle (AgNP) based antibacterial surfaces were fabricated using plasma polymerization technology and their effects on differentiation of human bone-marrow derived mesenchymal stem cells (hMSCs) were investigated in this study. The results showed that AgNP coated surfaces do not affect the initial adhesion, spreading and proliferation of hMSCs. Furthermore, the silver coated surface promoted adipogenic differentiation of hMSCs as demonstrated by more accumulation of lipid droplets and upregulation of adipogenesis-related genes such as peroxisome proliferator activated receptor gamma (PPARγ), adipocyte determination and differentiation factor (ADD1) and CCAAT/enhancer binding protein alpha (C/EBPα). In addition, silver incorporation activated the expression of antioxidant enzymes as a consequence of the accumulation of intracellular reactive oxygen species (ROS) in adipogenic induced cells, which was correlated with the enhanced adipogenic capacity of hMSCs. ROS generation was enhanced due to silver ion release and consequently reduced osteogenesis at the early stage after 7 days of osteogenic induction as a result of reducing alkaline phosphatase (ALP) activity. However, the differentiation and mineralization capacity of osteoblasts were restored after 14 days of osteogenic induction, which indicated that adipogenesis favors intracellular ROS accumulation mediated by silver coatings compared to osteogenesis. None of the osteogenic related genes was affected by ROS mediated by AgNP dissolution. The findings in this work are instructive for the use of silver as an antibacterial agent in the areas of tissue engineering, stem cell therapies and implantable biomedical devices.

Exploiting a new glycerol-based copolymer as a route to wound healing: Synthesis, characterization and biocompatibility assessment

The use of biocompatible materials based on naturally derived monomers plays a key role in pharmaceutical and cosmetic industries. In this paper we describe the synthesis of a new low molecular weight copolymer, based on glycerol and l-tartaric acid, useful to develop biocompatible dermal patches with drug delivery properties. The copolymer's chemical composition was assessed by FT-IR (Fourier transform infrared spectroscopy), (1)H NMR ((1)H Nuclear Magnetic Resonance) and XPS (X-ray photoelectron spectroscopy), while its molecular weight distribution was estimated by SEC (size exclusion chromatography). Copolymer thermal properties were studied by TGA (thermogravimetric analysis). Biological evaluations by MTT assay and SEM (scanning electron microscopy) observations performed with murine fibroblasts and human keratinocytes (HaCaT) revealed a good compatibility of the proposed copolymer. Ciprofloxacin was selected as model drug and its release was evaluated by HPLC (high performance liquid chromatography), showing that the new copolymer supplied promising results as drug delivery system for wound healing applications. Furthermore, investigations on Skin-Mesenchymal stem cells (S-MSCs) behaviour and gene expression showed that the copolymer and its combination with ciprofloxacin did not affect their stemness. In this regard, the fabrication of dermal patches with new, low cost materials for local treatment of skin infections represents an attractive strategy in order to bypass the worrying side effects of systemic antibiotic therapy. Overall, the performed physico-chemical characterization, drug release test and biological evaluations showed that this new copolymer could be a promising tool for the in situ delivery of bioactive molecules during skin lesions treatment.

A combinatorial variation in surface chemistry and pore size of three-dimensional porous poly(ε-caprolactone) scaffolds modulates the behaviors of mesenchymal stem cells

Biomaterial properties play significant roles in controlling cellular behaviors. The objective of the present study was to investigate how pore size and surface chemistry of three-dimensional (3D) porous scaffolds regulate the fate of mesenchymal stem cells (MSCs) in vitro in combination. First, on poly(ε-caprolactone) (PCL) films, the hydrolytic treatment was found to stimulate the adhesion, spreading and proliferation of human MSCs (hMSCs) in comparison with pristine films, while the aminolysis showed mixed effects. Then, 3D porous PCL scaffolds with varying pore sizes (100-200μm, 200-300μm and 300-450μm) were fabricated and subjected to either hydrolysis or aminolysis. It was found that a pore size of 200-300μm with hydrolysis in 3D scaffolds was the most favorable condition for growth of hMSCs. Importantly, while a pore size of 200-300μm with hydrolysis for 1h supported the best osteogenic differentiation of hMSCs, the chondrogenic differentiation was greatest in scaffolds with a pore size of 300-450μm and treated with aminolysis for 1h. Taken together, these results suggest that surface chemistry and pore size of 3D porous scaffolds may potentially have a synergistic impact on the behaviors of MSCs.