Immune checkpoint inhibitors have revolutionized treatment of many types of cancer, but are not effective for all patients. One proposed mechanism of resistance is lack of local interferon production that results in an immunologically “cold” tumor. This barrier may be overcome by direct immune stimulation with TLR9 agonists. Early phase clinical studies in a variety of cancer types have demonstrated intratumoral injection of TLR9 agonists, as free drug or formulated into nanoparticles (NP), is safe and capable of inducing systemic tumor regression alone or in combination with immune checkpoint inhibitors. Plasmacytoid dendritic cells (pDCs) are potent producers of type I interferon such as interferon alpha (IFN⍺). They are key immune system regulators and play a central role in the response to TLR9 agonists. BDCA2 is a cell surface receptor expressed uniquely on pDCs. Signaling through BDCA2 is thought to decrease the immune response initiated by pDCs, particularly in response to TLR agonists. Heparin is a BDCA2 ligand and has been shown to inhibit the TLR9 agonist-driven IFN⍺ response. We developed a novel heparin-coated, polyamidoamine (PAMAM) NP containing a TLR9 agonist to investigate whether heparin-mediated targeting of these NP to pDCs via BDCA2 modulates the pDC response to TLR9. Control NP included those without surface heparin and those without TLR9 agonists. Fresh normal donor human peripheral blood mononuclear cells (PBMCs) were treated with NP for 20 hours. Supernatants were collected for IFN⍺ ELISA to determine whether a functional PBMC response, mediated in large part by pDCs, was stimulated by the NP. Flow cytometric evaluation was used to assess whether NP induced a phenotypic change in pDCs. Heparin-coated NP containing a TLR9 agonist was more effective than soluble TLR9 agonist at inducing IFN⍺production from PBMCs. Such NP also increased expression of PD-L1 on pDCs. Increased IFN⍺ production and PD-L1 expression were most pronounced with TLR9-containing particles that had a high heparin coating amount. Of note, a low heparin coating amount resulted in reduced IFN⍺ production and PD-L1 expression on pDCs. The published literature suggests BDCA2 signaling inhibits pDC activation induced by TLR9 agonists. In contrast, here we show that TLR9-containing NP coated with high concentrations of the BDCA2 ligand heparin actually enhances activation of pDCs. Biologically, this suggests signaling via BDCA2 may vary based on the concentration of ligand or how it is presented. Therapeutically, heparin-coated NP containing TLR9 agonists may represent a promising novel approach for stimulating a local immune response, with potential relevance in both cancer immunotherapy and vaccination. Additional studies are ongoing to confirm NP activity is mediated by BDCA2 and to optimize NP composition. This includes assessment of various NP structural components, concentrations and types of BDCA2 ligands, and various TLR agonists. Greg Kirkpatrick, Caitlin Lemke-Miltner, Rui He, Sue Blackwell, Aliasger Salem, George J. Weiner. Novel heparin nanoparticles targeting BDCA2 promote immune response [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2025; Part 1 (Regular Abstracts); 2025 Apr 25-30; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2025;85(8_Suppl_1):Abstract nr 6164.

Chondrogenic differentiation of mesenchymal stem cells (MSCs) within a three-dimensional (3D) environment can be guided to form cartilage-like tissue in vitro to generate cartilage grafts for implantation. 3D bioprinted, MSC-populated cartilage grafts have the potential to replace autologous cartilage in reconstructive airway surgery. Here, bone marrow-derived ferret MSCs (fMSCs) capable of directed musculoskeletal differentiation were generated for the first time. A multi-material, 3D bioprinted fMSC-laden scaffold was then engineered that was capable of in vitro cartilage regeneration, as evidenced by glycosaminoglycan (GAG) production and collagen II immunohistochemical staining. In vivo implantation of these 3D bioprinted scaffolds in a ferret model of laryngotracheal reconstruction (LTR) demonstrated healing of the defect site, epithelial mucosalization of the inner lumen, and expansion of the airway volume. While the implanted scaffold allowed for reconstruction of the created airway defect, minimal chondrocytes were identified at the implant site. Nevertheless, we have established the ferret as a biomedical research model for airway reconstruction and, although further evaluation is warranted, the generation of fMSCs provides an opportunity for realizing the potential for 3D bioprinted regenerative stem cell platforms in the ferret.

Chemotherapy-induced peripheral neuropathy (CIPN) is a dose-limiting side effect of chemotherapy treatment, often resulting in the discontinuation of treatment. Paclitaxel activates peripheral macrophages, generating a neuroinflammatory response that contributes to CIPN development and maintenance. Astrocyte Elevated Gene-1 (AEG-1), also known as Metadherin or LYRIC, is a multifunctional protein that modulates macrophage activity and regulates inflammation through direct interaction with NF-κB, a transcriptional regulator of proinflammatory cytokine/chemokine (PIC) expression. We aimed to determine whether AEG-1 contributes to the development and maintenance of CIPN pathologies by using both global (AEG-1 KO) and myelocyte-specific knockout (AEG-1ΔMAC) transgenic mouse strains in an animal model of CIPN that replicates specific human clinical phenotypes. We hypothesized that inhibition of AEG1 expression in myeloid cells, such as monocytes and macrophages, would prevent the development and maintenance of CIPN. Our results showed that global AEG-1 deletion prevented the development of CIPN pathologies induced by PAC, as well as oxaliplatin (OHP). PAC treatment was found to increase AEG-1 and PIC expression in the DRGs of WT mice and in peritoneal macrophages isolated from C57BL/6J mice. However, in the absence of AEG-1 expression, PAC-induced neuroinflammation was completely halted in the DRGs of AEG-1 KO mice. This preventative phenotype and PIC expression profile was mirrored in AEG-1ΔMAC mice, which also displayed reduced NF-κB protein levels and F4/80+ macrophages trafficked to the lumbar DRGs following PAC treatment. In summary, our results are the first to demonstrate the biological role AEG-1, particularly in myeloid cells, in development of CIPN.

Cystic fibrosis is a serious life-threatening hereditary disease that occurs due to a mutation in the cystic fibrosis transmembrane conductance regulator gene (CFTR). Ivacaftor (IVA) is a drug that targets the mutated CFTR protein. IVA is highly hydrophobic (log P = 5.6) with poor aqueous solubility (0.05 µg/mL) and is formulated as an amorphous solid dispersion tablet under the brand name Kalydeco®. The recommended daily dose of Kalydeco® is twice per day with a high fat meal to aid in IVA’s absorption. In this research, we studied the application of cyclodextrins (CDs) to improve the dissolution of IVA. Phase solubility studies between IVA and four different CDs (α-, β-, γ-, and hydroxypropyl-β-CD [HP-β-CD]) were conducted and a significant improvement in IVA’s aqueous solubility with HP-β-CD was observed. Solid state characterizations confirmed the formation of IVA/HP-β-CD inclusion complexes. In vitro dissolution studies were conducted at pH = 6.8 and showed improvement in IVA’s rate and extent of dissolution with IVA/HP-β-CD (1:2) complexes in comparison to uncomplexed IVA. In vivo pharmacokinetics in mice showed a 2-fold increase in area under the curve (AUC) after the oral administration of the IVA/HP-β-CD complex in comparison to Kalydeco tablets. In addition, HP-β-CD extended the release of IVA from the IVA/HP-β-CD complexes with a longer Tmax of 7.05 h compared to 2.96 h with Kalydeco® tablets. These results demonstrate that CD inclusion complexes of IVA using HP-β-CD can be a successful alternative approach to improving the solubility of IVA while extending its release.

The activation of chondrogenic progenitor cells (CPCs) in articular cartilage during a traumatic injury is vital for cartilage regeneration. Although our understanding of the mechanisms underlying CPC chondrogenic activation remains incomplete, there is evidence that exosomal microRNAs (miRNAs or miRs) are involved in tissue healing due to their regulating role of posttranscriptional gene expressions. In this study, we profiled enriched and differential expression of miRNAs in exosomes derived from bovine joint cells (CPCs, chondrocytes, and synoviocytes) via Next Generation Sequencing analysis and validated the potential therapeutic effects of candidate exosomal miRNAs for cartilage regeneration. For CPC-based cartilage regeneration, we tested the impact of administering miR-107, miR-140, and miR-148a on CPCs because we found that these miRNAs were highly and differentially expressed in chondrocytes-derived exosomes (CC-Exo). We found that: (1) miR-140 induced chondrogenic gene expression including SRY-box transcription factor 9, collagen type 2A1, and aggrecan, and (2) miR-107 suppressed catabolic gene expression including matrix metalloproteinase 3, a disintegrin and metalloproteinase with thrombospondin motifs 5, and nitric oxide synthase 2. Our findings indicate that transfection of CPCs with specific chondrogenic miRNAs present in CC-Exo have the potential to promote CPC-based cartilage regeneration and could be an important component of posttraumatic osteoarthritis prevention. Impact Statement Chondrocytes, chondrogenic progenitor cells (CPCs), and synoviocytes secrete exosomal microRNAs (miRNAs) that contribute to joint health and disease. These miRNAs could also have important implications for improving cartilage repair and regeneration. In this study, we identified candidate miRNAs that were enriched in chondrocytes-derived exosomes and found that these miRNAs induced chondrogenic gene expression or suppressed catabolic gene expression in a CPC monolayer culture system. These findings suggest that miRNA-based cartilage repair strategies could be developed to regenerate damaged and diseased cartilage.

Large volume bone defects that do not spontaneously heal despite surgical stabilization (“critical-sized” defects) remain a challenge to treat clinically. Recent research investigating bone regenerative implants made from 3D printed materials have shown promise as a potential alternative to current treatment methods, such as autografting, allografting, and multi-step surgical interventions. Recent work has shown that implanting 3D printed calcium phosphate cement (CPC) scaffolds loaded with bone morphogenetic protein-2 (BMP-2) can provide a one-step surgical intervention that has similar bone healing outcomes to a popular two-step intervention: the Masquelet technique. The aim of this study was to investigate whether a 3D printed CPC scaffold loaded with a lyophilized polyplex gene-delivery formulation could serve as an alternative to loading BMP-2 protein onto such scaffolds. We 3D printed CPC scaffolds, hardened them with multiple methods, and explored the impact of these hardening methods on surface texture, mechanical strength, osteogenic differentiation, and ion flux. We then gene-activated these materials with cationic polyplexes containing plasmid DNA encoding reporter genes to investigate transfection from the gene-activated scaffolds. We found that incubating CPC scaffolds in aqueous solutions after initial hardening in a humid environment could enhance scaffold mechanical strength (compressive strength of 21.28 MPa vs. 6.54 MPa) and osteogenic differentiation. We also found that when we increased the total surface area of the CPC material exposed to polyplex solutions, there was a reduction in transfection via adsorption of polyplexes to the CPC surface. This study shows that 3D printed, gene-activated CPC scaffolds are a promising avenue for future exploration in the field of bone regeneration, though the level of gene expression induced by the scaffolds must be improved.

PURPOSE:Data on clear-cell renal cell carcinoma (ccRCC) xenografts defined the seleno-L-methionine (SLM) dose and the plasma selenium concentrations associated with the enhancement of hypoxia-inducible factor-1α/2α degradation, stabilization of tumor vasculature, enhanced drug delivery, and efficacy of axitinib. The data provided the rationale for the development of this phase I clinical trial of SLM and axitinib in advanced or metastatic relapsed ccRCC. PATIENTS AND METHODS:Patients were ≥18 years with histologically and radiologically confirmed advanced or metastatic ccRCC who had received at least one prior systemic therapy, which could include axitinib (last dose ≥6 months prior to enrollment). Escalating dose levels of SLM (2,500, 3,000, and 4,000 μg) were administered orally twice daily for 14 days and then once daily concurrently with axitinib 5 mg twice daily using a 3 + 3 design in phase I. Patients were treated at the 4,000 μg dose level in the expansion cohort to obtain preliminary estimates of efficacy. RESULTS:No dose-limiting toxicities occurred at the 4,000 μg SLM dose level. Among the 27 patients treated with 4,000 μg of SLM, the overall response rate was 55.6%, median duration of response was 18.4 months, median progression-free survival was 14.8 months, and median overall survival was 19.6 months. Preliminary results have shown that plasma selenium concentrations, inhibition of TGF-β1, and stabilization of tumor vasculature by SLM are time dependent. CONCLUSIONS:SLM (4,000 μg) in sequential combination with axitinib is well tolerated with encouraging efficacy.

Arthrofibrosis is defined as the excessive accumulation of connective tissue in and around joints, which interferes with the range of motion required for activities of daily living. Although joint stiffness can be restored by surgical interventions such as adhesion lysis, arthroscopic debridement, and capsular release, arthrofibrosis tends to redevelop in the months following the surgery. Thus, there is a critical and urgent need to develop a non-invasive, pharmacological therapy to prevent or resolve arthrofibrosis. A subclass of small extracellular vesicles called exosomes convey bioactive regulators like micro ribonucleic acids (miRNAs/miRs), which can function as anti- and pro-fibrotic agents. Currently, there is no research on miRNA-based therapeutic potentials for treating arthrofibrosis. Previous research and clinical observations on fibrosis across organ systems suggest that there are commonalities in pathogenic mechanisms that can be targeted in arthrofibrosis therapy. In this study, we collated and critically analyzed the existing literature on exosomal miRNAs in organ fibrosis to discover potential candidates for diagnosing, preventing, and/or treating arthrofibrosis. Fifty-six articles were finally selected and categorized by anti- and pro-fibrotic candidates of miRNAs. Notably, let-7, miR-26, miR-29, miR-146, miR-148/-152, miR-214, miR-223, and miR-21 emerged as prominent candidates that should be investigated further for effectiveness in arthrofibrosis therapy.

Radiotherapy (RT) can trigger immunogenic cell death which may be exploited to improve the effectiveness of immunotherapy. However, recent results from clinical trials testing RT/immunotherapy combinations in head and neck squamous cell carcinoma patients (HNSCC) have been disappointing. Interleukin-1 alpha (IL-1α) is a cytokine that can activate various aspects of anti-tumor immunity including dendritic cell (DC) activation which is critical for the recruitment of tumor infiltrating lymphocytes. Here we test the cytokine IL-1α encapsulated in 20:80 1,6‐bis‐(p‐carboxyphenoxy)‐hexane:sebacic acid (CPH:SA) copolymer-based microparticles (IL-1αMPs) as an adjuvant to RT in a murine syngeneic HNSCC mouse model. Thus the main research objective of this current study was to evaluate if IL-1αMPs can enhance the antitumor immune response of radiotherapy. Activation of immune cells in response to RT ± human recombinant IL-1α was evaluated in human peripheral blood mononuclear cell (PBMC):cancer cell co-cultures. A bilateral HNSCC tumor syngeneic mouse model was used to monitor mEERL tumor growth and immune cell recruitment in response to RT (8 Gy to irradiated tumor only) with and without intraperitoneal delivery of IL-1αMPs. Results showed that IL-1α induced the activation of monocytes, NK cells, T cells, and DCs in PBMC:Cal-27 cell co-cultures but there was no enhanced immune cell activation (with the exception of NK cells) in vitro when combined with RT. RT and RT + IL-1αMPs significantly suppressed growth in irradiated mEERL tumors compared to control. However, only the combination therapy was able to slowdown growth of the non-irradiated tumors compared to the other treatment groups. Immune cell profiling revealed that RT caused acute lymphodepletion on treatment day 3 which was reversed by treatment day 11 in RT-exposed mice. The anti-tumor effect of RT + IL-1α was accompanied by significantly increased infiltration of DCs in the irradiated tumor and increased CD8 + and antigen (E7)-specific CD8 + T cell infiltration in both irradiated and non-irradiated tumors. The anti-tumor response of the combination therapy was completely abrogated by CD8 + T cell depletion. This data suggests that the addition of CPH:SA IL-1αMPs to RT may boost anti-tumor immune response and target both local and systemic disease. This combination is worthy of further investigation as an immunotherapeutic strategy and could represent a promising approach to improve survival outcomes in HNSCC patients.

Reparative tertiary dentinogenesis requires the recruitment and odontogenic differentiation of dental pulp stem cells (DPSCs). Extracellular vesicles (EVs) as bioactive molecules have gained attention in regenerative medicine for their ability to mediate tissue repair through intercellular communication, influencing cell recruitment, proliferation, and differentiation. This study aimed to evaluate the effects of EVs on DPSC homing and odontogenic differentiation for dentin regeneration. DPSC-derived EVs were cultured in either growth (EV-G) or odontogenic differentiation (EV-O) conditions and isolated using a modified precipitation method. EVs were characterized by nanoparticle tracking analysis, scanning electron microscopy, antibody array, and cellular uptake assay. Treatment with 5 × 108 EVs/mL significantly enhanced DPSC chemotaxis and proliferation compared with a no-treatment control and a lower dosage of EV (5 × 107 EVs/mL). Gene expression and biochemical analyses revealed that EV-O up-regulated odontogenic markers including collagen type 1A1 (COL1A1), runt-related transcription factor 2 (RUNX2), and alkaline phosphatase (ALP). EV-O enhanced dentin regeneration by approximately 55% over vehicle controls in a rabbit partial dentinotomy/pulpotomy model. We identified key microRNAs (miR-21-5p, miR-221-3p, and miR-708-3p) in EV-O involved in cell homing and odontogenesis. In conclusion, our EV-based cell homing and odontogenic differentiation strategy has significant therapeutic potential for dentin regeneration.

Leukoplakia, a common type of oral dysplasia, is simply defined as a white patch in the mouth or other mucosal surface. Oral dysplasia is the most common premalignancy in the oral cavity and yet it is insufficiently researched and thus both diagnosing and treating oral dysplasia are still problematic issues. This study focuses on the immune signature of oral dysplasia and explores whether stimulating the immune system with an immune therapy, vidutolimod (± immune checkpoint blockade (ICB)), can prevent the progression of oral dysplasia or even cause regression. Vidutolimod, a virus-like particle encapsulating G10, is believed to activate plasmacytoid dendritic cells (pDCs) through the activation of the Toll-like receptor 9 (TLR9). To investigate this, an established murine model for inducing oral cancer was used to study oral dysplasia development and response to in situ injection of vidutolimod at the premalignant phase. The effect of treatment was analyzed histologically and immunologically. ELISA revealed significantly elevated levels of IFN-γ, IL-12, and TNF-α in the sera of mice after 24 h of one treatment with vidutolimod + ICB as well as increased levels of proliferating T cells and pDCs in draining lymph nodes 72 h after the third and final treatment, thus indicating the immune-boosting effect of this therapy. Vidutolimod + ICB caused a significant decrease in Ki-67 expression by epithelial cells in the lesion area compared to untreated mice, implicating that this treatment regime may prevent lesion progression.

PURPOSE. Evidence suggests that corneal endothelial cell (CEC) death in Fuchs endothelial corneal dystrophy (FECD) is due to ferroptosis, an iron-mediated cell death. Iron-sulfur cluster (ISC)-containing aconitases and the iron responsive element binding proteins IREBP1 and IREBP2 are known mediators of iron homeostasis. This study investigates mechanisms underlying iron dysregulation in CECs and proposes a role for ISCs and IREBPs in the context of FECD pathogenesis. METHODS. We studied gene expression of proteins responsible for ISC synthesis and iron homeostasis in human and mouse CECs and analyzed published RNA sequencing datasets. We validated a subset of transcriptional changes between FECD and control tissues using microfluidic Western blotting with human CEC tissues. Finally, we silenced proteins involved in ISC synthesis or iron homeostasis in cell cultures and assessed ferroptosis susceptibility. RESULTS. RNA-seq and qPCR data demonstrated significantly decreased transcription of genes required for ISC synthesis in FECD tissues (P < 0.05). Protein quantification revealed a significant decrease in mitochondrial aconitase (P < 0.05), ferredoxin 1 (P < 0.001), and mitofusin (P < 0.05), and a significant increase in cysteine desulfurase (P < 0.05), cytosolic aconitase/IREBP1, and IREBP2 (P < 0.05) in FECD tissues. Silencing studies revealed increased susceptibility to ferroptosis upon siRNA knockdown of ferredoxin 1 (P < 0.05). CONCLUSIONS. We identified differential gene expression of proteins responsible for ISC synthesis, ISC-containing proteins, IREBPs that mediate cellular iron homeostasis, and mitofusin, which promotes mitochondrial fusion in FECD. We also identified increased susceptibility to ferroptosis after ferredoxin 1 knockdown in CECs. These results advance an ISC-and IREBP-mediated mechanism of iron accumulation in FECD CECs.

Radiation exposure occurs during medical procedures, nuclear accidents, or spaceflight, making effective medical countermeasures a public health priority. Naïve T cells are highly sensitive to radiation-induced depletion, although their numbers recover with time. Circulating memory CD8+ T cells are also depleted by radiation; however, their numbers do not recover. Critically, the impact of radiation exposure on tissue-resident memory T cells (TRM) remains unknown. Here, we found that sublethal thorax-targeted radiation resulted in the rapid and prolonged numerical decline of influenza A virus (IAV)–specific lung TRM in mice, but no decline in antigen-matched circulating memory T cells. Prolonged loss of lung TRM was associated with decreased heterosubtypic immunity. Importantly, boosting with IAV-epitope expressing pathogens that replicate in the lungs or peripheral tissues or with a peripherally administered mRNA vaccine regenerated lung TRM that was derived largely from circulating memory CD8+ T cells. Designing effective vaccination strategies to regenerate TRM will be important in combating the immunological effects of radiation exposure.

Fuchs endothelial corneal dystrophy (FECD), the leading indication for corneal transplantation in the U.S., causes loss of corneal endothelial cells (CECs) and corneal edema leading to vision loss. FECD pathogenesis is linked to impaired response to oxidative stress and environmental ultraviolet A (UVA) exposure. Although UVA is known to cause nonapoptotic oxidative cell death resulting from iron-mediated lipid peroxidation, ferroptosis has not been characterized in FECD. We investigated the roles of genetic background and UVA exposure in causing CEC degeneration in FECD. Using ungenotyped FECD patient surgical samples, we found increased levels of cytosolic ferrous iron (Fe2+) and lipid peroxidation in end-stage diseased tissues compared with healthy controls. Using primary and immortalized cell cultures modeling the TCF4 intronic trinucleotide repeat expansion genotype, we found altered gene and protein expression involved in ferroptosis compared to controls including elevated levels of Fe2+, basal lipid peroxidation, and the ferroptosis-specific marker transferrin receptor 1. Increased cytosolic Fe2+ levels were detected after physiologically relevant doses of UVA exposure, indicating a role for ferroptosis in FECD disease progression. Cultured cells were more prone to ferroptosis induced by RSL3 and UVA than controls, indicating ferroptosis susceptibility is increased by both FECD genetic background and UVA. Finally, cell death was preventable after RSL3 induced ferroptosis using solubilized ubiquinol, indicating a role for anti-ferroptosis therapies in FECD. This investigation demonstrates that genetic background and UVA exposure contribute to iron-mediated lipid peroxidation and cell death in FECD, and provides the basis for future investigations of ferroptosis-mediated disease progression in FECD.

Titanium and its alloys are widely used materials for biomedical devices including orthopedic/dental implants. However, peri-implantitis is associated with recurrent surgeries and remains problematic and therefore a biocompatible approach is required to reduce instances of infection. Herein, we report on the antimicrobial potential (against key oral pathogens) and biocompatibility of a novel metronidazole-loaded chitosan formulation (coating titanium surfaces) and compare the findings with those obtained for metronidazole-loaded poly-(lactide-co-glycolide) (PLGA) coatings. Titanium disc surfaces were coated with defined metronidazole-loaded polymer-based formulations and physicochemically characterized using scanning electron microscopy (SEM), Raman spectroscopy, X-ray powder diffraction (XRD), and differential scanning calorimetry (DSC). Metronidazole released at each time point was measured using high-pressure liquid chromatography (HPLC). Antimicrobial activity of the coatings was assessed using agar disk diffusion method. Biocompatibility of the coatings was evaluated using live/dead stain confocal imaging and MTS cell proliferation assay. Osseointegration was determined by measuring BMP-2 protein expression using ELISA. PLGA coatings exhibited a smooth surface morphology, whereas the chitosan coatings exhibited a rough structure. Raman spectroscopy, XRD, and DSC data indicated no evidence of physicochemical incompatibility issues of metronidazole with PLGA and high and low molecular weight chitosan. Metronidazole delivered via high ( n = 3, p < 0.01) and low molecular weight chitosan ( n = 3, p < 0.01) coatings had significantly enhanced antimicrobial activity against Prevotella intermedia ( P. intermedia ) compared to when delivered via PLGA coatings ( n = 3). Treponema denticola was also tested and was found to be significantly susceptible to metronidazole loaded in low molecular weight chitosan ( n = 3, p < 0.05) compared to when delivered via PLGA coatings ( n = 3). In addition, chitosan coatings were shown to be more biocompatible and with good osseointegration potential compared to PLGA coatings as demonstrated by higher cell viability and bone morphogenic protein-2 (BMP-2) levels, respectively. A titanium implant surface coated with metronidazole that is delivered via chitosan was successfully developed and can be considered as an appealing strategy for prevention and treatment of peri-implant infection.

Elbow trauma can lead to joint contracture and reduced range of motion (ROM). Nonsurgical interventions can improve ROM, but in some cases capsule release surgery is required. Although surgery can improve ROM, it often does not restore full ROM. Thus, alternatives are needed. One approach is to target activated myofibroblasts, which are commonly associated with fibrotic tissue. Mechanical and biochemical cues drive a feedback loop that can result in normal or pathological healing. We hypothesize that this feedback loop exists in joint contracture and can be manipulated so that myofibroblast activity is reduced, normal healing is achieved, and ROM is improved. We previously demonstrated that blebbistatin can inhibit myofibroblast contractile forces and reduce collagen synthesis in vitro. Thus, the purpose of this study was to assess the use of blebbistatin in an animal model of elbow contracture, which was induced in 7 groups of 4 rats each (n = 28). All elbows were mechanically and histologically tested. The uninjured contralateral elbows of each rat were used as a control group. Capsule release surgery significantly improved (p < 0.01) outcomes 1 week after surgery compared to injury alone and was not significantly different from uninjured elbows. Three weeks after surgery, outcomes worsened, indicating joint stiffening consistent with what is observed clinically. The addition of blebbistatin did not significantly improve outcomes. Future work will investigate relationships among treatment, fibrotic tissue deposition, myofibroblast activity, and biomechanics to determine if blebbistatin is a useful adjunctive therapy for treating joint contracture.