Anti-fibrotic effect of pirfenidone in muscle derived-fibroblasts from Duchenne muscular dystrophy patients

Pirfenidone improves voiding function by suppressing bladder fibrosis in underactive bladder rats

Underactive bladder (UAB), characterized by a complex set of symptoms with few treatment options, can significantly reduce the quality of life of affected people. UAB is characterized by hyperplasia and fibrosis of the bladder wall as well as decreased bladder compliance. Pirfenidone is a powerful anti-fibrotic agent that inhibits the progression of fibrosis in people with idiopathic pulmonary fibrosis. In the current study, we evaluated the efficacy of pirfenidone in the treatment of bladder fibrosis in a UAB rat model. UAB was induced by crushing damage to nerve bundles in the major pelvic ganglion. Forty-two days after surgery, 1 mL distilled water containing pirfenidone (100, 300, or 500 mg/kg) was orally administered once every 2 days for a total of 10 times for 20 days to the rats in the pirfenidone-treated groups. Crushing damage to the nerve bundles caused voiding dysfunction, resulting in increased bladder weight and the level of fibrous related factors in the bladder, leading to UAB symptoms. Pirfenidone treatment improved urinary function, increased bladder weight and suppressed the expression of fibrosis factors. The results of this experiment suggest that pirfenidone can be used to ameliorate difficult-to-treat urological conditions such as bladder fibrosis. Therefore, pirfenidone treatment can be considered an option to improve voiding function in patient with incurable UAB.

Innovative Substrate Design with Basement Membrane Components for Enhanced Endothelial Cell Function and Endothelization

Enhancing endothelial cell growth on small-diameter vascular grafts produced from decellularized tissues or synthetic substrates is pivotal for preventing thrombosis. While optimized decellularization protocols can preserve the structure and many components of the extracellular matrix (ECM), the process can still lead to the loss of crucial basement membrane proteins, such as laminin, collagen IV, and perlecan, which are pivotal for endothelial cell adherence and functional growth. This loss can result in poor endothelialization and endothelial cell activation causing thrombosis and intimal hyperplasia. To address this, the basement membrane's ECM is emulated on fiber substrates, providing a more physiological environment for endothelial cells. Thus, fibroblasts are cultured on fiber substrates to produce an ECM membrane substrate (EMMS) with basement membrane proteins. The EMMS then underwent antigen removal (AR) treatment to eliminate antigens from the membrane while preserving essential proteins and producing an AR-treated membrane substrate (AMS). Subsequently, human endothelial cells cultured on the AMS exhibited superior proliferation, nitric oxide production, and increased expression of endothelial markers of quiescence/homeostasis, along with autophagy and antithrombotic factors, compared to those on the decellularized aortic tissue. This strategy showed the potential of pre-endowing fiber substrates with a basement membrane to enable better endothelization.

Extracellular Matrix Proteomics: The mdx-4cv Mouse Diaphragm as a Surrogate for Studying Myofibrosis in Dystrophinopathy

The progressive degeneration of the skeletal musculature in Duchenne muscular dystrophy is accompanied by reactive myofibrosis, fat substitution, and chronic inflammation. Fibrotic changes and reduced tissue elasticity correlate with the loss in motor function in this X-chromosomal disorder. Thus, although dystrophinopathies are due to primary abnormalities in the DMD gene causing the almost-complete absence of the cytoskeletal Dp427-M isoform of dystrophin in voluntary muscles, the excessive accumulation of extracellular matrix proteins presents a key histopathological hallmark of muscular dystrophy. Animal model research has been instrumental in the characterization of dystrophic muscles and has contributed to a better understanding of the complex pathogenesis of dystrophinopathies, the discovery of new disease biomarkers, and the testing of novel therapeutic strategies. In this article, we review how mass-spectrometry-based proteomics can be used to study changes in key components of the endomysium, perimysium, and epimysium, such as collagens, proteoglycans, matricellular proteins, and adhesion receptors. The mdx-4cv mouse diaphragm displays severe myofibrosis, making it an ideal model system for large-scale surveys of systematic alterations in the matrisome of dystrophic fibers. Novel biomarkers of myofibrosis can now be tested for their appropriateness in the preclinical and clinical setting as diagnostic, pharmacodynamic, prognostic, and/or therapeutic monitoring indicators.

Pirfenidone Has Anti-fibrotic Effects in a Tissue-Engineered Model of Human Cardiac Fibrosis

A fundamental process in the development and progression of heart failure is fibrotic remodeling, characterized by excessive deposition of extracellular matrix proteins in response to injury. Currently, therapies that effectively target and reverse cardiac fibrosis are lacking, warranting novel therapeutic strategies and reliable methods to study their effect. Using a gelatin methacryloyl hydrogel, human induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CM) and human fetal cardiac fibroblasts (hfCF), we developed a multi-cellular mechanically tunable 3D in vitro model of human cardiac fibrosis. This model was used to evaluate the effects of a promising anti-fibrotic drug-pirfenidone-and yields proof-of-concept of the drug testing potential of this platform. Our study demonstrates that pirfenidone has anti-fibrotic effects but does not reverse all TGF-β1 induced pro-fibrotic changes, which provides new insights into its mechanism of action.

Role of Human Primary Renal Fibroblast in TGF-β1-Mediated Fibrosis-Mimicking Devices

Renal fibrosis is a progressive chronic kidney disease that ultimately leads to end-stage renal failure. Despite several approaches to combat renal fibrosis, an experimental model to evaluate currently available drugs is not ideal. We developed fibrosis-mimicking models using three-dimensional (3D) co-culture devices designed with three separate layers of tubule interstitium, namely, epithelial, fibroblastic, and endothelial layers. We introduced human renal proximal tubular epithelial cells (HK-2), human umbilical-vein endothelial cells, and patient-derived renal fibroblasts, and evaluated the effects of transforming growth factor-β (TGF-β) and TGF-β inhibitor treatment on this renal fibrosis model. The expression of the fibrosis marker alpha smooth muscle actin upon TGF-β1 treatment was augmented in monolayer-cultured HK-2 cells in a 3D disease model. In the vascular compartment of renal fibrosis models, the density of vessels was increased and decreased in the TGF-β-treated group and TGF-β-inhibitor treatment group, respectively. Multiplex ELISA using supernatants in the TGF-β-stimulating 3D models showed that pro-inflammatory cytokine and growth factor levels including interleukin-1 beta, tumor necrosis factor alpha, basic fibroblast growth factor, and TGF-β1, TGF-β2, and TGF-β3 were increased, which mimicked the fibrotic microenvironments of human kidneys. This study may enable the construction of a human renal fibrosis-mimicking device model beyond traditional culture experiments.

Extracellular matrix: an important regulator of cell functions and skeletal muscle development

Extracellular matrix (ECM) is a kind of connective tissue in the cell microenvironment, which is of great significance to tissue development. ECM in muscle fiber niche consists of three layers: the epimysium, the perimysium, and the endomysium (basal lamina). These three layers of connective tissue structure can not only maintain the morphology of skeletal muscle, but also play an important role in the physiological functions of muscle cells, such as the transmission of mechanical force, the regeneration of muscle fiber, and the formation of neuromuscular junction. In this paper, detailed discussions are made for the structure and key components of ECM in skeletal muscle tissue, the role of ECM in skeletal muscle development, and the application of ECM in biomedical engineering. This review will provide the reader with a comprehensive overview of ECM, as well as a comprehensive understanding of the structure, physiological function, and application of ECM in skeletal muscle tissue.

Nanomedicine for Gene Delivery and Drug Repurposing in the Treatment of Muscular Dystrophies

Muscular Dystrophies (MDs) are a group of rare inherited genetic muscular pathologies encompassing a variety of clinical phenotypes, gene mutations and mechanisms of disease. MDs undergo progressive skeletal muscle degeneration causing severe health problems that lead to poor life quality, disability and premature death. There are no available therapies to counteract the causes of these diseases and conventional treatments are administered only to mitigate symptoms. Recent understanding on the pathogenetic mechanisms allowed the development of novel therapeutic strategies based on gene therapy, genome editing CRISPR/Cas9 and drug repurposing approaches. Despite the therapeutic potential of these treatments, once the actives are administered, their instability, susceptibility to degradation and toxicity limit their applications. In this frame, the design of delivery strategies based on nanomedicines holds great promise for MD treatments. This review focuses on nanomedicine approaches able to encapsulate therapeutic agents such as small chemical molecules and oligonucleotides to target the most common MDs such as Duchenne Muscular Dystrophy and the Myotonic Dystrophies. The challenge related to in vitro and in vivo testing of nanosystems in appropriate animal models is also addressed. Finally, the most promising nanomedicine-based strategies are highlighted and a critical view in future developments of nanomedicine for neuromuscular diseases is provided.

TAK1 inhibition improves myoblast differentiation and alleviates fibrosis in a mouse model of Duchenne muscular dystrophy

BACKGROUND

Transforming growth factor-β-activated kinase 1 (TAK1) plays a key role in regulating fibroblast and myoblast proliferation and differentiation. However, the TAK1 changes associated with Duchenne muscular dystrophy (DMD) are poorly understood, and it remains unclear how TAK1 regulation could be exploited to aid the treatment of this disease.

METHODS

Muscle biopsies were obtained from control donors or DMD patients for diagnosis (n = 6 per group, male, 2-3 years, respectively). Protein expression of phosphorylated TAK1 was measured by western blot and immunofluorescence analysis. In vivo overexpression of TAK1 was performed in skeletal muscle to assess whether TAK1 is sufficient to induce or aggravate atrophy and fibrosis. To explore whether TAK1 inhibition protects against muscle damage, mdx (loss of dystrophin) mice were treated with adeno-associated virus (AAV)-short hairpin TAK1 (shTAK1) or NG25 (a TAK1 inhibitor). Serum analysis, skeletal muscle performance and histology, muscle contractile function, and gene and protein expression were performed.

RESULTS

We found that TAK1 was activated in the dystrophic muscles of DMD patients (n = 6, +72.2%, P < 0.001), resulting in fibrosis ( +65.9% for fibronectin expression, P < 0.001) and loss of muscle fibres (-32.5%, P < 0.01). Moreover, TAK1 was activated by interleukin-1β, tumour necrosis factor-α, and transforming growth factor-β1 (P < 0.01). Overexpression of TAK1 by AAV vectors further aggravated fibrosis (n = 8, +39.6% for hydroxyproline content, P < 0.01) and exacerbated muscle wasting (-31.6%, P < 0.01) in mdx mice; however, these effects were reversed in mdx mice by treatment with AAV-short hairpin TAK1 (shTAK1) or NG25 (a TAK1 inhibitor). The molecular mechanism underlying these effects may be related to the prevention of TAK1-mediated transdifferentiation of myoblasts into fibroblasts, thereby reducing fibrosis and increasing myoblast differentiation.

CONCLUSIONS

Our findings show that TAK1 activation exacerbated fibrosis and muscle degeneration and that TAK1 inhibition can improve whole-body muscle quality and the function of dystrophic skeletal muscle. Thus, TAK1 inhibition may constitute a novel therapy for DMD.

Nutritional intervention with cyanidin hinders the progression of muscular dystrophy

Muscular Dystrophies are severe genetic diseases due to mutations in structural genes, characterized by progressive muscle wasting that compromises patients' mobility and respiratory functions. Literature underlined oxidative stress and inflammation as key drivers of these pathologies. Interestingly among different myofiber classes, type I fibers display a milder dystrophic phenotype showing increased oxidative metabolism. This work shows the benefits of a cyanidin-enriched diet, that promotes muscle fiber-type switch and reduced inflammation in dystrophic alpha-sarcoglyan (Sgca) null mice having, as a net outcome, morphological and functional rescue. Notably, this benefit is achieved also when the diet is administered in dystrophic animals when the signs of the disease are seriously evident. Our work provides compelling evidence that a cyanidin-rich diet strongly delays the progression of muscular dystrophies, paving the way for a combinatorial approach where nutritional-based reduction of muscle inflammation and oxidative stress facilitate the successful perspectives of definitive treatments.

Theme 3 In vitro experimental models

Background: Ongoing disease gene discoveries continue to drive our understanding of the molecular and cellular mechanisms underlying ALS. Causative genes from 60% of ALS families have been identified using modern genetic techniques, but the causal gene defect is yet to be identified in the remaining 40% of families. These remaining families often do not follow true Mendelian inheritance patterns and are challenging to solve using traditional genetic analysis alone. In vitro and in vivo studies have become critical in assessing and validating these ALS candidate genes.Objectives: In this study, we aim to develop and validate the utility of an in vitro functional pipeline for the discovery and validation of novel ALS candidate genes.Methods: A panel of cell based-assays were applied to candidate genes to examine the presence/absence of known ALS pathologies in cell lines as well as human autopsy tissues. These include immunofluorescence, flow cytometry and western blotting to study toxicity, neuronal inclusion formation, interaction with TDP-43, aberrant protein degradation and accumulation in detergent-insoluble cellular fractions. Immunohistochemistry and immunofluorescence were also used to examine if candidates were present in neuronal inclusions from ALS patient spinal cord tissues.Results: The in vitro pipeline was applied to five candidate genes from an ALS family that is negative for known ALS gene mutations. Two candidates were prioritized as top candidates based on their capacity to induce known ALS cellular pathologies. In transfected cells, the variants in these two genes caused a significantly higher toxicity than wild type, formed detergent insoluble inclusions and was able to co-aggregate with TDP-43 in neuronal cells. The variants have also led to protein degradation defects. One of the candidates also co-localised with TDP-43-positive neuronal inclusions in sporadic ALS patient post-mortem tissues, a signature pathology of ALS.Discussion and conclusions: We have demonstrated the utility of a functional prioritization pipeline and successfully prioritized two novel candidate ALS genes. These genes, and its associated pathways, will be further investigated through the development of animal models to establish if there is support for its role in ALS. New ALS genes offer fresh diagnostic and therapeutic targets and tools for the generation of novel animal models to better understand disease biology and offer preclinical testing of candidate treatments for ALS in the future.

Low intensity training improves redox status and reduces collagen fibers on dystrophic muscle

Exercise therapy on skeletal muscle of muscular dystrophies has no defined parameters. The effect of low-intensity treadmill training on the oxidative stress markers and fibrosis on hindlimb muscles was investigated. Sixteen dystrophic male mdx animals were separated in trained (mdxT/n=8) and untrained (mdxNT/n=8) groups. Wild type animals (WT/n=8) were used as healthy control. The mdxT group runned at a horizontal treadmill (9 m/min, 30 min/day, 3 times/wk, 8 weeks). Gastrocnemius and tibial anterior muscles were collected for analysis of enzymatic/non-enzymatic oxidant activity, oxidative damage concentration, collagen fibers area morphometry. The mdxT group presented a lower collagen fiber area compared to mdxNT for gastrocnemius (P=0.025) and tibial anterior (P=0.000). Oxidative damage activity was higher in the mdxT group for both muscles compared to mdxNT. Catalase presented similar activity for tibial anterior (P=0.527) or gastrocnemius (P=0.323). Superoxide dismutase (P=0.003) and total antioxidant capacity (P=0.024) showed increased activity in the mdxT group at tibial anterior with no difference for gastrocnemius. Low-intensity training is considered therapeutic as it reduces collagen deposition while improving tissue redox status.

The antifibrotic drug pirfenidone inhibits spondyloarthritis fibroblast-like synoviocytes and osteoblasts in vitro

Background

The pathogenesis of spondyloarthritis (SpA) involves both inflammation and new bone formation in the spine. In line with this, the disease has been characterized as both inflammatory and fibrotic. The current treatment dampens inflammation while new bone formation can progress. Therefore, there is an unmet therapeutic need for the treatment of new bone formation in SpA. Fibrosis is mediated by myofibroblasts and new bone formation is the result of increased osteoblast mineralization and decreased osteoclast resorption. Here, we evaluate the potential effect of the newly approved anti-fibrotic agent pirfenidone (PFD) on fibrosis and new bone formation in cell culture models of SpA.

Methods

Fibroblast-like synoviocytes (FLSs) were isolated from SpA patients (n = 6) while the osteoblast cell line Saos-2 was purchased. The cells were cultured with PFD at 0.25 0.5, or 1.0 mg/ml. The proliferation of FLSs was analyzed with light microscopy and flow cytometry. The differentiation and activation of FLSs was assessed with flow cytometry, a membrane-based antibody array and enzyme-linked immunosorbant assays. The mineralization capacity of osteoblasts was studied with an assay measuring deposition of hydroxyapatite.

Results

PFD reduced the Ki67 expression 7.1-fold in untreated FLSs (p = 0.001) and 11.0-fold in FLSs stimulated with transforming growth factor beta (TGFβ), tumor necrosis factor alpha (TNFα), and interferon gamma (IFNγ) (p = 0.022). There were no statistically significant changes in membrane expression of alpha smooth muscle actin (αSMA), intercellular adhesion molecule 1 (ICAM-1), or human leukocyte antigen DR (HLA-DR). In supernatants from FLSs stimulated with TGFβ, TNFα, and IFNγ, PFD decreased the secretion of 3 of 12 proteins more than 2-fold in the membrane-based antibody array. The changes in secretion of monocyte chemoattractant protein 1 (MCP-1) and chitinase-3-like protein 1 (CHI3L1, YKL-40) were validated with ELISA. PFD decreased the secretion of both Dickkopf-related protein 1 (DKK1) (p = 0.006) and osteoprotegerin (OPG) (p = 0.02) by SpA FLSs stimulated with TGFβ, TNFα, and IFNγ. Finally, PFD inhibited the deposition of hydroxyapatite by osteoblasts in a dose-dependent manner (p = 0.0001).

Conclusions

PFD inhibited SpA FLS proliferation and function and osteoblast mineralization in vitro. This encourages studies of the in vivo effect of PFD in SpA.

Establishment of a complex skin structure via layered co-culture of keratinocytes and fibroblasts derived from induced pluripotent stem cells

Background

Skin is an organ that plays an important role as a physical barrier and has many other complex functions. Skin mimetics may be useful for studying the pathophysiology of diseases in vitro and for repairing lesions in vivo. Cord blood mononuclear cells (CBMCs) have emerged as a potential cell source for regenerative medicine. Human induced pluripotent stem cells (iPSCs) derived from CBMCs have great potential for allogenic regenerative medicine. Further study is needed on skin differentiation using CBMC-iPSCs.

Methods

Human iPSCs were generated from CBMCs by Sendai virus. CBMC-iPSCs were differentiated to fibroblasts and keratinocytes using embryonic body formation. To generate CBMC-iPSC-derived 3D skin organoid, CBMC-iPSC-derived fibroblasts were added into the insert of a Transwell plate and CBMC-iPSC-derived keratinocytes were seeded onto the fibroblast layer. Transplantation of 3D skin organoid was performed by the tie-over dressing method.

Results

Epidermal and dermal layers were developed using keratinocytes and fibroblasts differentiated from cord blood-derived human iPSCs, respectively. A complex 3D skin organoid was generated by overlaying the epidermal layer onto the dermal layer. A humanized skin model was generated by transplanting this human skin organoid into SCID mice and effectively healed skin lesions.

Conclusions

This study reveals that a human skin organoid generated using CBMC iPSCs is a novel tool for in-vitro and in-vivo dermatologic research.

Electronic supplementary material

The online version of this article (10.1186/s13287-018-0958-2) contains supplementary material, which is available to authorized users.

Pirfenidone reduces profibrotic responses in human dermal myofibroblasts, in vitro

Pirfenidone (PFD) is a synthetic small molecule inhibitor with demonstrated anti-inflammatory and antifibrotic properties in vitro and in vivo. The exact mechanism(s) of PFD action remain unclear, due in part to the broad effects of this drug on the complex processes involved in inflammation and fibrosis. While PFD is FDA-approved for the treatment of idiopathic pulmonary fibrosis, the efficacy of this compound for the treatment of dermal fibrosis has not yet been fully characterized. Dermal fibrosis is the pathological formation of excess fibrous connective tissue of the skin, usually the result of traumatic cutaneous injury. Fibroproliferative scarring, caused by delayed wound healing and prolonged inflammation, remains a major clinical concern with considerable morbidity. Despite efforts to identify a therapeutic that targets the fibrotic pathways involved in wound healing to mitigate scar formation, no satisfactory dermal antifibrotic has yet been identified. We aim to better elucidate the antifibrotic mechanism(s) of PFD activity using an in vitro model of dermal fibrosis. Briefly, cultured human dermal fibroblasts were stimulated with TGF-β1 to induce differentiation into profibrotic myofibroblast cells. A dose-dependent reduction in cellular proliferation and migration was observed in TGF-β1-stimulated cells when treated with PFD. We observed a clear inhibition in the development of essential myofibroblast mechanoregulatory machinery, including contractile F-actin stress fibers containing α-SMA and large super-mature focal adhesions. PFD treatment significantly reduced protein levels of major ECM components type I and type III collagen. PFD targeted the p38 MAPK signaling pathway and mitigated profibrotic gene expression profiles. This in vitro data promotes PFD as a potential therapeutic agent for the treatment of dermal fibrosis.

Tackling muscle fibrosis: From molecular mechanisms to next generation engineered models to predict drug delivery

Muscle fibrosis represents the end stage consequence of different diseases, among which muscular dystrophies, leading to severe impairment of muscle functions. Muscle fibrosis involves the production of several growth factors, cytokines and proteolytic enzymes and is strictly associated to inflammatory processes. Moreover, fibrosis causes profound changes in tissue properties, including increased stiffness and density, lower pH and oxygenation. Up to now, there is no therapeutic approach able to counteract the fibrotic process and treatments directed against muscle pathologies are severely impaired by the harsh conditions of the fibrotic environment. The design of new therapeutics thus need innovative tools mimicking the obstacles posed by the fibrotic environment to their delivery. This review will critically discuss the role of in vivo and 3D in vitro models in this context and the characteristics that an ideal model should possess to help the translation from bench to bedside of new candidate anti-fibrotic agents.

Test of Antifibrotic Drugs in a Cellular Model of Fibrosis Based on Muscle-Derived Fibroblasts from Duchenne Muscular Dystrophy Patients

An in vitro model of muscle fibrosis, based on the use of primary human fibroblasts isolated from muscle biopsies of patients affected by Duchenne muscular dystrophies (DMD) and cultivated in monolayer and 3D conditions, is used to test the potential antifibrotic activity of pirfenidone (PFD). This in vitro model may be usefully also to evaluate the toxicity and efficacy of other candidate molecules for the treatment of fibrosis. The drug toxicity is evaluated using a colorimetric assay based on the conversion of tetrazolium salt (MTT) to insoluble formazan, while the effect of the drug on cell proliferation is measured with the bromodeoxyuridine incorporation assay. The efficacy of the drug is evaluated in fibroblast monolayers by quantitating synthesis and deposition of intracellular collagen with a spectrophotometric picrosirius red-based assay, and by quantitating cell migration using a "scratch" assay. The efficacy of PFD as antifibrotic drug is also evaluated in a 3D fibroblast model by measuring diameters and number of nodules.

Pharmacological therapeutics targeting the secondary defects and downstream pathology of Duchenne muscular dystrophy

INTRODUCTION

Since the identification of the dystrophin gene in 1986, a cure for Duchenne muscular dystrophy (DMD) has yet to be discovered. Presently, there are a number of genetic-based therapies in development aimed at restoration and/or repair of the primary defect. However, growing understanding of the pathophysiological consequences of dystrophin absence has revealed several promising downstream targets for the development of therapeutics.

AREAS COVERED

In this review, we discuss various strategies for DMD therapy targeting downstream consequences of dystrophin absence including loss of muscle mass, inflammation, fibrosis, calcium overload, oxidative stress, and ischemia. The rationale of each approach and the efficacy of drugs in preclinical and clinical studies are discussed.

EXPERT OPINION

For the last 30 years, effective DMD drug therapy has been limited to corticosteroids, which are associated with a number of negative side effects. Our knowledge of the consequences of dystrophin absence that contribute to DMD pathology has revealed several potential therapeutic targets. Some of these approaches may have potential to improve or slow disease progression independently or in combination with genetic-based approaches. The applicability of these pharmacological therapies to DMD patients irrespective of their genetic mutation, as well as the potential benefits even for advanced stage patients warrants their continued investigation.

Preparation of novel pirfenidone microspheres for lung-targeted delivery: in vitro and in vivo study

The aim of this study was to develop and characterize pirfenidone (PF)-loaded chitosan microspheres for lung targeting. The microspheres were prepared using the emulsion-solvent evaporation method and characterized by assessing morphology, particle size, and zeta potential. The microspheres had a spherical nature with highly smooth and integrated surfaces. The particle size of microspheres was 4.6±0.3 µm, and the zeta potential was 20.3±1.4 mV. The in vitro release results indicated that the obtained formulation of PF could reach the state of sustained release with a biphasic drug release pattern. It was observed that there was no significant difference in both the percentage of entrapment efficiency and that of drug release before and after the stability study. In vivo, the calculated relative bioavailability indicated greater pulmonary absorption of PF when it was encapsulated in microspheres. According to histopathological studies, no histological change occurred to the rat lung after the administration of PF-loaded chitosan microspheres.

Pro-fibrotic effects of PFKFB4-mediated glycolytic reprogramming in fibrous dysplasia

Fibrous dysplasia (FD) caused by a mosaic somatic mutation of GNAS is characterized by replacement of the affected bone with abnormal fibrous tissue. Herein, we present novel disease models for FD developed with pairs of isogenic wild-type and GNAS(R201H)-mutated induced pluripotent stem cells (iPSCs) and their derivative mesenchymal stem cells (MSCs). Both 2D and 3D MSC culture models for FD successfully reflect FD's typical molecular characteristics, such as enhanced cAMP level, PKA activity, CREB1 phosphorylation and the pathologic fibrotic phenotype. The fibrotic features of GNAS(R201H) FD model cells were closely linked to augmented glycolysis and depended on glycolytic PFKFB4 and the activation of pro-fibrotic TGFβ signalling. Either depletion of PFKFB4 or inhibition of glycolysis or TGFβ signalling potentially blocked fibrosis progression in GNAS(R201H) FD model cells. Our FD models could facilitate a better mechanistic understanding of FD and help develop effective therapeutics for FD and other fibrosis diseases.