Development of cisplatin-loaded hydrogels for trans-portal vein chemoembolization in an orthotopic liver cancer mouse model.

Transarterial chemoembolization is a standard treatment for intermediate-stage hepatocellular carcinoma (HCC). This study evaluated the anti-tumor effect of the semi-interpenetrating network (IPN) hydrogel as a novel embolic material for trans-portal vein chemoembolization (TPVE) in vivo. A nude mice orthotopic HCC model was established, followed by TPVE using IPN hydrogel loaded with or without cisplatin. Portal vein blockade was visualized by MRI and the development of tumor was monitored by IVIS Spectrum Imaging. Tumor proliferation and angiogenesis were evaluated by Ki67 and CD34 staining respectively. Intra-tumor caspase 3, Akt, ERK1/2, and VEGF activation were detected by Western Blot. 18 F-FMISO uptake was evaluated by microPET-MRI scanning. IPN hydrogel first embolized the left branch of portal vein within 24 hours and further integrated into the intra-tumor vessels during 2 weeks after the treatment. Mice treated with cisplatin-loaded hydrogels exhibited a significant decrease in tumor growth, along with lower plasma AFP levels as compared to hydrogel-treated and untreated tumor-bearing mice. By Ki67 and CD34 staining, the TPVE with IPN hydrogel suppressed tumor proliferation and angiogenesis. In addition, increased tumor apoptosis shown by up-regulation of caspase 3 with decreased expressions of tumor cell survival indicators Akt and ERK1/2 were observed in the treatment groups. Consistent with the decreased expression of VEGF after TPVE, hypoxia level in the tumor was also reduced as indicated by 18 F-FMISO uptake level. IPN hydrogel-based TPVE significantly suppressed the tumor development by regulating intra-tumor angiogenesis and cell survival in an orthotopic HCC mouse model, suggesting a viable embolic agent for transarterial chemoembolization.

Multifunctional Microparticles Incorporating Gold Compound Inhibit Human Lung Cancer Xenograft.

PURPOSE: Gold porphyrin (AuP) is a complex that has been shown to be potent against various tumors. A biocompatible interpenetrating network (IPN) system comprised of polyethyleneglycol diacrylate (PEGdA) and chemically-modified gelatin has been shown to be an effective implantable drug depot to deliver AuP locally. Here we designed IPN microparticles complexed with AuP to facilitate intravenous administration and to diminish systemic toxicity. METHODS: We have synthesized and optimized an IPN microparticle formulation complexed with AuP. Tumor cell cytotoxicity, antitumor activity, and survival rate in lung cancer bearing nude mice were analyzed. RESULTS: IPN microparticles maintained AuP bioactivity against lung cancer cells (NCI-H460). In vivo study showed no observable systemic toxicity in nude mice bearing NCI-H460 xenografts after intravenous injection of 6 mg/kg AuP formulated with IPN microparticles. An anti-tumor activity level comparable to free AuP was maintained. Mice treated with 6 mg/kg AuP in IPN microparticles showed 100% survival rate while the survival rate of mice treated with free AuP was much less. Furthermore, microparticle-formulated AuP significantly reduced the intratumoral microvasculature when compared with the control. CONCLUSION: AuP in IPN microparticles can reduce the systemic toxicity of AuP without compromising its antitumor activity. This work highlighted the potential application of AuP in IPN microparticles for anticancer chemotherapy.

Anti-tumour effects of PIM kinase inhibition on progression and chemoresistance of hepatocellular carcinoma.

Hepatocellular carcinoma (HCC) is a biologically aggressive cancer. Targeted therapy is in need to tackle challenges in the treatment perspective. A growing body of evidence suggests a promising role of pharmacological inhibition of PIM (proviral integration site for Moloney murine leukaemia virus) kinase in some human haematological and solid cancers. Yet to date, the potential application of PIM inhibitors in HCC is still largely unexplored. In the present study we investigated the pre-clinical efficacy of PIM inhibition as a therapeutic approach in HCC. Effects of PIM inhibitors on cell proliferation, migration, invasion, chemosensitivity, and self-renewal were examined in vitro. The effects of PIM inhibitors on tumour growth and chemoresistance in vivo were studied using xenograft mouse models. Potential downstream molecular mechanisms were elucidated by RNA sequencing (RNA-seq) of tumour tissues harvested from animal models. Our findings demonstrate that PIM inhibitors SGI-1776 and PIM447 reduced HCC proliferation, metastatic potential, and self-renewal in vitro. Results from in vivo experiments supported the role of PIM inhibition in suppressing of tumour growth and increasing chemosensitivity of HCC toward cisplatin and doxorubicin, the two commonly used chemotherapeutic agents in trans-arterial chemoembolisation (TACE) for HCC. RNA-seq analysis revealed downregulation of the MAPK/ERK pathway upon PIM inhibition in HCC cells. In addition, LOXL2 and ICAM1 were identified as potential downstream effectors. Taken together, PIM inhibitors demonstrated remarkable anti-tumourigenic effects in HCC in vitro and in vivo. PIM kinase inhibition is a potential approach to be exploited in formulating adjuvant therapy for HCC patients of different disease stages. © 2020 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.

A Multifunctional Hydrogel Delivers Gold Compound and Inhibits Human Lung Cancer Xenograft.

PURPOSE: Interpenetrating network system (IPN), consisting of polyethylene glycol (PEG) -diacrylate (PEGdA) and modified gelatin, is a biocompatible and biodegradable hydrogel and has been studied for the local delivery of bioactive molecules and drugs. Gold(III) porphyrin(AuP) is a stable metal compound in the development for anticancer application when administered systemically. The aim of this work is to develop a novel formulation for AuP based on IPN for local delivery. METHODS: IPN loaded with AuP hydrogel was optimized and synthesized. Drug release kinetics, cytotoxicity against tumor cells, and antitumor activity in lung cancer bearing nude mice were studied. RESULTS: AuP released from the IPN followed a first order kinetics in vitro. The AuP loaded IPN showed higher cytotoxicity against human lung cancer cell lines compared to IPN only. In mice bearing human lung cancer xenograft, AuP loaded IPN inhibited tumor growth and reduced angiogenesis. No sign of systemic toxicity was observed for all treatment groups. CONCLUSION: AuP loaded IPN provides an improved formulation over systemic delivery for tumor inhibition to complement surgical intervention. Graphical Abstract Injectable multifunctional matrix of polyethylene glycol and gelatin derivatives for the delivery of gold porphyrinto inhibit tumor growth.

Mesenchymal Stromal/Stem Cell and Minocycline-Loaded Hydrogels Inhibit the Growth of Staphylococcus aureus that Evades Immunomodulation of Blood-Derived Leukocytes.

Mesenchymal stromal/stem cells (MSCs) have demonstrated favorable wound healing properties in addition to their differentiation capacity. MSCs encapsulated in biomaterials such as gelatin and polyethylene glycol (PEG) composite hydrogels have displayed an immunophenotype change that leads to the release of cytokines and growth factors to accelerate wound healing. However, therapeutic potential of implanted MSC-loaded hydrogels may be limited by non-specific protein adsorption that facilitates adhesion of bacterial pathogens such as planktonic Staphylococcus aureus (SA) to the surface with subsequent biofilm formation resistant to immune cell recognition and antibiotic activity. In this study, we demonstrate that blood-derived primary leukocytes and bone marrow-derived MSCs cannot inhibit colony-forming abilities of planktonic or biofilm-associated SA. However, we show that hydrogels loaded with MSCs and minocycline significantly inhibit colony-forming abilities of planktonic SA while maintaining MSC viability and multipotency. Our results suggest that minocycline and MSC-loaded hydrogels may decrease the bioburden of SA at implant sites in wounds, and may improve the wound healing capabilities of MSC-loaded hydrogels.

Cell encapsulating biomaterial regulates mesenchymal stromal/stem cell differentiation and macrophage immunophenotype.

Bone marrow mesenchymal stromal/stem cell (MSC) encapsulation within a biomatrix could improve cellular delivery and extend survival and residence time over conventional intravenous administration. Although MSCs modulate monocyte/macrophage (Mø) immunophenotypic properties, little is known about how such interactions are influenced when MSCs are entrapped within a biomaterial. Furthermore, the impact of the cell-encapsulating matrix on MSC multipotency and on Møs, which infiltrate biomaterials, remains poorly understood. Here we elucidate this three-way interaction. The Mø immunophenotype and MSC differentiation were examined with regard to established and experimental collagen-based biomaterials for MSC entrapment. Tumor necrosis factor-α secretion was acutely inhibited at 4 days. MSCs cocultured with Møs demonstrated attenuated chondrocyte differentiation, whereas osteoblast differentiation was enhanced. Adipocyte differentiation was considerably enhanced for MSCs entrapped within the gelatin/polyethylene glycol-based matrix. A better understanding of the effect of cell encapsulation on differentiation potency and immunomodulation of MSCs is essential for MSC-based, biomaterial-enabled therapies.

Thiol-ene-based biological/synthetic hybrid biomatrix for 3-D living cell culture.

Although various cell encapsulation materials are available commercially for a wide range of potential therapeutic cells, their combined clinical impact remains inconsistent. Synthetic materials such as poly(ethylene glycol) (PEG) hydrogels are mechanically robust and have been extensively explored but lack natural biofunctionality. Naturally derived materials including collagen, fibrin and alginate-chitosan are often labile and mechanically weak. In this paper we report the development of a hybrid biomatrix based on the thiol-ene reaction of PEG diacrylate (PEGdA) and cysteine/PEG-modified gelatin (gel-PEG-Cys). We hypothesized that covalent crosslinking decreases gelatin dissolution thus increasing gelatin resident time within the matrix and the duration of its biofunctionality; at the same time the relative ratio of PEGdA to gel-PEG-Cys in the matrix formulation directly affects hydrogel bulk and local microenvironment properties. Bulk viscoelastic properties were highly dependent on PEGdA concentration and total water content, while gel-PEG-Cys concentration was more critical to swelling profiles. Microviscoelastic properties were related to polymer concentration. The covalently crosslinked gel-PEG-Cys with PEGdA decreased gelatin dissolution out of the matrix and collagenase-mediated degradation. Fibroblasts and keratinocyte increased adhesion density and formed intercellular connections on stiffer hydrogel surfaces, while cells exhibited more cytoplasmic spreading and proliferation when entrapped within softer hydrogels. Hence, this material system contains multiparametric factors that can easily be controlled to modulate the chemical, physical and biological properties of the biomatrix for soft tissue scaffolding and cell presentation to reconstruct lost tissue architecture and physical functionality.

Active leukocyte detachment and apoptosis/necrosis on PEG hydrogels and the implication in the host inflammatory response.

Monocytes/Macrophages have long been recognized as key players in inflammation and wound healing and are often employed in vitro to gain an understanding of the inflammatory response to biomaterials. Previous work has demonstrated a drastic decrease in primary monocyte adherent density on biomaterial surfaces coupled with a change in monocyte behavior over time. However, the mechanism responsible for this decrease remains unclear. In this study, we explored active detachment and cellular death as possible regulating factors. Specifically, extracellular TNF-α and ROS production were analyzed as potential endogenous stimulators of cell death. MMPs, but not calpains, were found to play a key role in active monocyte detachment. Monocyte death was found to peak at 24 h and occur by both apoptosis and necrosis as opposed to polymorphonuclear leukocyte death which mainly occurred through apoptosis. Finally, TNF-α and ROS production were not found to have a causal relationship with monocyte death on TCPS or PEG surfaces. The occurrence of primary monocyte apoptosis/necrosis as well as active detachment from a material surface has implications not only in in vitro study, but also in the translation of the in vitro inflammatory response of these cells to in vivo applications.

Multifunctional Biomaterial Matrix for Advanced Wound Healing.

BACKGROUND: Modern wound dressings provide a moist healing environment and facilitate faster and higher quality of healing. A new semi-interpenetrating network (sIPN) biomaterial platform based on poly(ethylene glycol) (PEG) and gelatin was developed as a multi-functional matrix for wound care. THE PROBLEM: Besides providing a moist environment and facilitating the healing process, advanced wound dressings may be designed to serve as delivery matrices for drugs and therapeutic cells. New and effective treatments should also comply with clinical settings and be easy to use. No single treatment exists today that can fulfill all these requirements; however, advancement in multifunctional biomaterial design and development holds promise to fill this technology gap. BASIC/CLINICAL SCIENCE ADVANCES: PEG + gelatin sIPN provides an ideal platform for fundamental research in cell-cell and cell-biomaterial interaction that is important in wound healing. The in situ forming ability of sIPN facilitates its use in large and irregular wounds with complex contours and crevices. CLINICAL CARE RELEVANCE: Although various commercially available wound dressings have been produced, a low-cost, easy-to-use, and biofunctionalizable biomaterial that provides a moist environment and facilitates healing is still a target of active tissue regeneration research. CONCLUSION: Extensive preclinical data support the use of in situ polymerized sIPN in advanced wound care.

Transbuccal Delivery of CNS Therapeutic Nanoparticles: Synthesis, Characterization, and In Vitro Permeation Studies.

This work utilized polyamidoamine (PAMAM) dendrimer G4.5 as the underlying carrier to construct CNS therapeutic nanoparticles and explored the buccal mucosa as an alternative absorption site for administration of the dendritic nanoparticles. Opioid peptide DPDPE was chosen as a model CNS drug. It was coupled to PAMAM dendrimer G4.5 with polyethylene glycol (PEG) or with PEG and transferrin receptor monoclonal antibody OX26 (i.e., PEG-G4.5-DPDPE and OX26-PEG-G4.5-DPDPE). The therapeutic dendritic nanoparticles labeled with 5-(aminoacetamido) fluorescein (AAF) were studied for transbuccal transport using a vertical Franz diffusion cell system mounted with porcine buccal mucosa. For comparison, AAF-labeled PAMAM dendrimers G3.5 and G4.5, and fluorescein isothiocynate (FITC)-labeled G3.0 and G4.0 were also tested for transbuccal delivery. The permeability of PEG-G4.5 (AAF)-DPDPE and OX26-PEG-G4.5(AAF)-DPDPE were on the order of 10(-7) - 10(-6) cm/s. Coadministration of bile salt sodium glycodeoxycholate (NaGDC) enhanced the permeability of dendritic nanoparticles by multiple folds. Similarly, a multifold increase of permeability of dendritic nanoparticles across the porcine buccal mucosal resulted from the application of mucoadhesive gelatin/PEG semi-interpenetrating network (sIPN). These results indicate that transbuccal delivery is a possible route for administration of CNS therapeutic nanoparticles.

In situ forming poly(ethylene glycol)-based hydrogels via thiol-maleimide Michael-type addition.

The incorporation of cells and sensitive compounds can be better facilitated without the presence of UV or other energy sources that are common in the formation of biomedical hydrogels such as poly(ethylene glycol) hydrogels. The formation of hydrogels by the step-growth polymerization of maleimide- and thiol-terminated poly(ethylene glycol) macromers via Michael-type addition is described. The effects of macromer concentration, pH, temperature, and the presence of biomolecule gelatin on gel formation were investigated. Reaction kinetics between maleimide and thiol functional groups were found to be rapid. Molecular weight increase over time was characterized via gel permeation chromatography during step-growth polymerization. Swelling and degradation results showed incorporating gelatin enhanced swelling and accelerated degradation. Increasing gelatin content resulted in the decreased storage modulus (G'). The in vitro release kinetics of fluorescein isothiocyanate (FITC)-labeled dextran from the resulting matrices demonstrated the potential in the development of novel in situ gel-forming drug delivery systems. Moreover, the resulting networks were minimally adhesive to primary human monocytes, fibroblasts, and keratinocytes thus providing an ideal platform for further biofunctionalizations to direct specific biological response.

Fetal bovine serum xenoproteins modulate human monocyte adhesion and protein release on biomaterials in vitro.

Monocyte-derived macrophages are critical in the host-foreign body response to biomaterials and have been studied extensively in various culture conditions in vitro, such as medium supplemented with fetal bovine serum (FBS) or autologous human serum (AHS). Since monocyte maturation into macrophages is highly plastic and may vary considerably depending on the surface, isolation procedures and in vitro culture conditions, we hypothesize that variations in protein adsorption and serum type will greatly impact monocyte behavior in a surface-dependent manner. The impact of xenoproteins on monocyte-surface interactions has not been well studied methodically and the use of AHS rather than FBS for macrophage-biomaterials studies in vitro is far from universal. The commonly used reference materials - tissue culture polystyrene (TCPS), polyethylene glycol (PEG) and polydimethylsiloxane (PDMS) - were employed in this study and we found a 3-fold higher adherent monocyte density on TCPS when AHS was used vs. FBS-supplemented medium. On PEG hydrogels, an 8- to 10-fold higher adhesion density was observed when AHS was employed vs. FBS, while on PDMS no difference in adhesion density was observed between the two sera conditions. Additionally, the presence of lipopolysaccharide abrogated the serum-dependent effect on cell adhesion on TCPS. Significantly different variations in protein release were observed between the serum conditions on these surfaces; in particular, there was a 100-fold higher concentration of growth-related oncogene for the AHS condition on PDMS even though the adhesion levels were comparable between the two serum conditions. These results emphasize the combined impact of the surface type and FBS xenoproteins in mediating the observed monocyte response to biomaterials in vitro.

Drug release kinetics and transport mechanisms of non-degradable and degradable polymeric delivery systems.

IMPORTANCE OF THE FIELD: The advancement in material design and engineering has led to the rapid development of new materials with increasing complexity and functions. Both non-degradable and degradable polymers have found wide applications in the controlled delivery field. Studies on drug release kinetics provide important information into the function of material systems. To elucidate the detailed transport mechanism and the structure-function relationship of a material system, it is critical to bridge the gap between the macroscopic data and the transport behavior at the molecular level. AREAS COVERED IN THIS REVIEW: The structure and function information of selected non-degradable and degradable polymers have been collected and summarized from literature published after the 1990s. The release kinetics of selected drug compounds from various material systems is discussed in case studies. Recent progress in the mathematical models based on different transport mechanisms is highlighted. WHAT THE READER WILL GAIN: This article aims to provide an overview of structure-function relationships of selected non-degradable and degradable polymers as drug delivery matrices. TAKE HOME MESSAGE: Understanding the structure-function relationship of the material system is key to the successful design of a delivery system for a particular application. Moreover, developing complex polymeric matrices requires more robust mathematical models to elucidate the solute transport mechanisms.

Multifunctional photopolymerized semiinterpenetrating network (sIPN) system containing bupivacaine and silver sulfadiazine is an effective donor site treatment in a swine model.

Previously, we have shown in a cross-comparison study that multifunctional photopolymerized semiinterpenetrating network (sIPN) system is an effective donor site treatment in a swine model. The advantages of sIPN include spray-on application, in situ photopolymerization, and ability to cover large contoured areas. sIPN has also been shown to be an effective delivery vehicle for keratinocyte growth factor, dexamethasone, bupivacaine, and silver sulfadiazine in vitro. Our aim for this study was to show that these products delivered to the wound bed with sIPN would not change the wound healing characteristics compared with the control site through qualitative clinical evaluation and to compare the rate and quality of donor site healing through histologic evaluation. Eight Yucatan swine of 40 lbs each were randomly divided into four groups of two pigs before surgery. Each animal had 5.6% TBSA of skin harvested from two different dorsal regions, with one at 22/1000th-inch and the other at 30/1000th-inch setting on the dermatome. Each test site on each animal was then sequentially dressed with 50 cm(2) of Xeroform gauze, sIPN, sIPN loaded with 0.5% bupivacaine, or sIPN loaded with 1% silver sulfadiazine. sIPN with or without soluble drugs were applied as liquid, then photopolymerized in situ to form an elastic covering. Each of the test areas was separated by 50 cm(2) of autograft, which was used to divide the test areas. Wound assessment and killing occurred at days 7, 9, 14, and 21. A full-thickness biopsy was taken from each of the study areas for histological analysis. By 14 days, all areas showed complete epidermal coverage histologically. The 30/1000th-inch site revealed a thicker, more irregular dermis compared with the 22/1000th-site. Evaluation of the day-21 sites revealed equal thinning and flattening of the new epidermis. No site showed full restoration of the rete ridges. No signs of infection were seen in clinical or histological evaluations of any treatment. The addition of bupivacaine and silver sulfadiazine to sIPN does not show any alterations in wound healing of a donor site in a swine model when compared with sIPN without loaded drugs and a standard control dressing. This efficacy may be coupled with established localized sIPN drug delivery profiles and allow further studies to evaluate the efficacy of these drugs to promote healing, eradicate and prevent infection, and manage pain.

Drug release kinetics and transport mechanisms from semi-interpenetrating networks of gelatin and poly(ethylene glycol) diacrylate.

PURPOSE: To elucidate the key parameters affecting solute transport from semi-interpenetrating networks (sIPNs) comprised of poly(ethylene glycol) diacrylate (PEGdA) and gelatin that are partially crosslinked, water-swellable and biodegradable. Effects of material compositions, solute size, solubility, and loading density have been investigated. MATERIALS AND METHODS: sIPNs of following gelatin/PEGdA weight-to-weight ratios were prepared: 10:15, 10:20, 10:30, 15:15, 20:15. Five model solutes of different physicochemical properties were selected, i.e. silver sulfadiazine (AgSD), bupivacaine hydrochloride (Bup), sulfadiazine sodium (NaSD), keratinocyte growth factor (KGF), and bovine serum albumin conjugated with fluorescein isothiocyanate (BSA-FITC). Release studies were performed and the results were analyzed using three hydrogel based common theories (free volume, hydrodynamic and obstruction). RESULTS: The release kinetics of model solutes was influenced by each factor under investigation. Specifically, the initial release rates and intra-gel diffusivity decreased with increasing PEGdA content or increasing solute molecular weight. However, the initial release rate and intra-gel diffusivity increased with increasing gelatin content or increasing solute water solubility, which contradicted with the classical hydrogel based solute transport theories, i.e. increasing polymer volume leads to decreased solute diffusivity within the gel. CONCLUSION: This analysis provides structure-functional information of the sIPN as a potential therapeutic delivery matrix.

Fibroblasts regulate monocyte response to ECM-derived matrix: the effects on monocyte adhesion and the production of inflammatory, matrix remodeling, and growth factor proteins.

Monocytes/macrophages and fibroblasts are recruited to the injury site and orchestrate the host response and tissue repair. We have previously shown that polyethylene glycol (PEG)-ylated arginine-glycine-aspartic acid (RGD) sequence grafted onto an extracellular matrix (ECM)-based semi-interpenetrating network (sIPN) enhances monocyte adhesion, and modulates subsequent gene expression and release of inflammatory and matrix remodeling factors. In this study, we investigate the direct influence of fibroblasts on monocyte response to this ECM mimic. Key wound-healing factors in inflammation, matrix remodeling, and regeneration were analyzed to gain insight into the interrelated role of regulation in fibroblast-monocyte interaction. Interleukin-1alpha/-1beta (IL-1alpha/-1beta), interleukin-6 (IL-6), tumor necrosis factor- alpha (TNF-alpha), monocyte inflammatory protein-1alpha/-1beta (MIP-1alpha/-1beta), transforming growth factor-alpha (TGF-alpha), monocyte chemoattractant factor (MCP-1), matrix metalloproteinase-2/-9 (MMP-2/-9), vascular endothelial growth factor (VEGF), granulocyte-macrophage colony-stimulating factor (GM-CSF) were analyzed. Fibroblasts decreased monocyte adhesion onto the RGD-grafted sIPN while increasing monocyte GM-CSF on all surfaces over time except for on RGD and PHSRN-grafted sIPN at 96 h. Monocytes decreased initial fibroblast IL-1alpha and TGF-alpha, but drastically increased fibroblast MMP-2 and GM-CSF. Monocyte IL-1beta, TNF-alpha, MIP-1beta, MCP-1, MMP-9, and GM-CSF expression was increased over time in the presence of all sIPNs, and when the sIPNs were immobilized with ligands, a down-regulation of fibroblast IL-1beta, MIP-1alpha, MIP-1beta compared with unmodified sIPN was observed. When the ligand immobilized was RGD, monocyte TGF-alpha, MIP-1beta, and VEGF expression was increased while monocyte GM-CSF was decreased at selected time points. These results showed a dynamic monocyte response to selected ECM components in the presence of fibroblasts.

Modulation of the keratinocyte-fibroblast paracrine relationship with gelatin-based semi-interpenetrating networks containing bioactive factors for wound repair.

Gelatin-based semi-interpenetrating networks (sIPNs) containing soluble and covalently-linked bioactive factors have been shown to aid in wound healing; however, the biological responses elicited by the introduction of sIPN biomaterials remain unclear. In the current study, modulation of the re-epithelialization phase of wound healing by sIPNs grafted with PEGylated fibronectin-derived peptides and utilized as platforms for the delivery of exogenous keratinocyte growth factor (KGF) was evaluated. Following wounding, keratinocyte migration, proliferation and protein secretion is largely controlled by diffusible factors, such as KGF, released by the underlying fibroblasts. The impact of sIPNs and exogenous KGF upon the latter keratinocyte-fibroblast paracrine relationship and keratinocyte behavior was explored by monitoring keratinocyte adhesion and cytokine (IL-1alpha, IL-1beta, IL-6, KGF, GM-CSF and TGF-alpha) release. Results were generally similar for keratinocyte monoculture and keratinocyte-fibroblast co-culture systems. Although keratinocyte adhesion increased over time for positive control surfaces, adhesion to the sIPNs remained low throughout the course of the study. Release of IL-1alpha and GM-CSF was increased by exogenous KGF. The effects were more noticeable on the positive control surfaces relative to the sIPN surfaces. Regulation of the release of TGF-alpha was surface dependent, while IL-6 release was dependent upon surface type, the inclusion of exogenous KGF and the presence of fibroblasts. The findings indicate that during re-epithelialization, sIPNs containing soluble bioactive factors aid in wound healing primarily by serving as conduits for KGF, which induces the release of other key cytokines involved in tissue repair.

Multifunctional in situ photopolymerized semi-interpenetrating network system is an effective donor site dressing: a cross comparison study in a swine model.

Effective dressings for donor sites or other partial thickness wounds must promote removal of nonviable or necrotic tissue, eradication and prevention of microbial infiltrate, exudate absorbance, and regrowth of healthy epidermis and dermis. There are many commonly used products that facilitate these processes. Established properties of an in situ photopolymerizable semi-interpenetrating network (sIPN) suggest that it is also a viable treatment option. The widely varying material properties suggest that these dressing treatments may elicit different healing responses via different cellular mechanisms. In this study, we sought to resolve the differences in healing between Acticoat, sIPN, nonadherent dressing with Tisseel, and Xeroform dressing treatments in a porcine partial thickness wound model. Donor site wounds were produced on pigs at two cut depths and dressed with Acticoat, sIPN, nonadherent dressing with Tisseel, and Xeroform with alternatively placed autografts to provide a control area between each test site. Pigs were euthanized at 4, 7, 14, and 42 days for macroscopic examination and biopsy collection. Biopsies were analyzed histologically by two blinded observers for cellular densities and regional thicknesses within the tissue. sIPN- and Xeroform-treated wounds were healed by 7 days, and Acticoat- and nonadherent dressing with Tisseel-treated wounds were healed by 14 days. Inflammatory responses were between comparable treatment type across all time periods. Dermal granulation features increased with time but were not significantly different. All dressing treatments elicited wound healing without outstanding toxicity or pathology indicating that sIPN is a comparable and viable treatment for partial thickness wounds.

Monocyte inflammatory and matrix remodeling response modulated by grafted ECM-derived ligand concentration.

Ligands presented on biomaterials are a common method to facilitate and control the host response. In a gelatin and polyethylene glycol diacrylate (PEGdA) based semi-interpenetrating network (sIPN), the effects of extracellular matrix (ECM)-derived peptide amount on monocyte adhesion and subsequent protein and mRNA expression were examined. Peptide amount on the sIPN surface was controlled by varying the wt % ratio of the peptide-PEG grafted gelatin to PEGdA. We hypothesized that increasing bioactive peptide amount would modulate human blood-derived monocyte adhesion, cytokine expression, and gene regulation. Monocyte adhesion, release of gelatin degrading proteases matrix metalloprotease-2 (MMP-2), matrix metalloprotease-9 (MMP-9), and proinflammatory protein interleukin-1beta (IL-1beta), and mRNA expression of these proteins were evaluated. We found RGD-PEG grafted sIPNs with higher surface RGD concentrations showed increased adherent density. MMP-2 and IL-1beta protein release was also influenced by the ligand concentration, as initial increase in protein concentration was observed at higher ligand concentrations. MMP-9 protein showed an initial increase that subsided then increased. A decreased IL-1beta protein and mRNA expression was observed over time but MMP-2 mRNA was not detected at any time though MMP-2 protein concentrations showed an initial burst. Hence, monocyte behavior was modulated by surface ligand identity in tandem with ligand concentration.

Concurrent in vitro release of silver sulfadiazine and bupivacaine from semi-interpenetrating networks for wound management.

In situ photopolymerized semi-interpenetrating networks (sIPNs) composed of poly(ethylene glycol) and gelatin are promising multifunctional matrices for a regenerative medicine approach to dermal wound treatment. In addition to previously demonstrated efficacy in critical defects, sIPNs also function as drug delivery matrices for compounds loaded as either soluble or covalently linked components. Simultaneous release of silver sulfadiazine and bupivacaine from the sIPN would provide multiple-hit management of dermal wounds that minimizes infection, and manages pain along with sIPN absorption of exudates and facilitation of epidermal regrowth. We characterized the release of soluble silver sulfadiazine and bupivacaine and compared it with an established release model. Efficacy of released silver sulfadiazine was confirmed in vitro on Staphylococcus aureus, methicillin resistant S. aureus, and Pseudomonas aeruginosa. Bupivacaine loaded without silver sulfadiazine showed incomplete release, whereas simultaneous loading with silver sulfadiazine facilitated 100% bupivacaine release. Silver sulfadiazine released at 98% without bupivacaine and 96% with bupivacaine. Silver sulfadiazine released onto bacterial cultures inhibited all three strains dose dependently. sIPNs effectively release bupivacaine and silver sulfadiazine while maintaining the antimicrobial activity of silver sulfadiazine. Drug loaded sIPNs have potential to improve wound management by providing multi-drug delivery along with an effective wound treatment.