Biology subjects

Siegel, A. E.

Publications and source records attributed to Siegel, A. E..

4 recordsLinked to original sources

bioRxiv2026

Activation of PPARγ redirects fibro-adipogenic progenitors to replace ectopic bone with fat in models of fibrodysplasia ossificans progressiva and trauma-induced heterotopic ossification

The pathologic, osteogenic differentiation of fibroadipogenic progenitor cells (FAPs) is the primary recognized contributor to ectopic bone formation in fibrodysplasia ossificans progressiva (FOP) and trauma-induced heterotopic ossification (HO). Both conditions are characterized by up-regulated BMP signaling - the former by a gene mutation rendering the BMP receptor ACVR1 susceptible to activation by inflammatory ligands (Activin A), and the latter by up-regulated presence of BMP2 ligand in the setting of unmutated BMP receptor. We performed an unbiased assessment of FDA-approved therapies which would optimally target the transcriptional aberrations observed in developing FOP and HO lesions based on publicly-available datasets. This analysis uncovered rosiglitazone, a peroxisome proliferator-activated receptor gamma (PPAR{gamma}) agonist as the highest scoring therapeutic option across three data sets for both conditions. Rosiglitazone treatment eliminated ectopic bone lesions in a mouse model of FOP, and replaced these lesions with ectopic adipose tissue; similarly, systemic and local rosiglitazone treatment eliminated ectopic bone lesions in a mouse model of trauma-induced HO and replaced these lesions with ectopic adipose tissue. Our findings were corroborated by a single case report from 2010 showing positive results with rosiglitazone in a non-diabetic patient with FOP, with no subsequent studies. Overall, our findings suggest that a previously FDA-approved therapeutic is likely to be a successful therapeutic agent for both FOP and trauma-induced HO, both conditions for which current therapeutic options remain inadequate. One Sentence SummaryWe show that a previously FDA-approved therapeutic known to induce adipogenesis reduces ectopic bone and induces ectopic fat formation in diseases of heterotopic ossification.

cell biology↗

bioRxiv2026

A closed-loop cell therapy engineered to autonomously secrete Activin A inhibitor protects from fibrodysplasia ossificans progressiva

Engineered cell therapies present an opportunity for endogenous, site-specific production of therapeutic agents. Here we describe a closed-loop cell therapy which secretes an inhibitor of Activin A, ActR2A-Fc, upon exposure to Activin A. We demonstrate in vivo therapeutic efficacy of this approach in a mouse model of fibrodysplasia ossificans progressiva (FOP), a morbid condition in which patients develop extensive heterotopic bony lesions in response to aberrant sensitivity to Activin A through a mutation in the type I BMP receptor ACVR1 (ACVR1 R206H). To blunt Activin A activity, we designed a transposon plasmid containing the transgene encoding ActR2A-Fc, with expression controlled by the BMP-responsive element (BRE). In cells containing the causative mutation, the BRE is pathologically activated upon exposure to Activin A. FOP-derived marrow cells modified with the BRE-ActR2AFc plasmid exhibited the desired closed-loop functionality, with increased ActR2A-Fc expression upon exposure to Activin A and reduced expression upon withdrawal of Activin A. Engineered marrow cells secreted bioactive ActR2A-Fc, and bone marrow transplantation of FOP marrow cells engineered with the BRE-ActR2AFc transposon into same-sex FOP mice resulted in absence of heterotopic bony lesions. Experiments with labeled, engineered FOP marrow cells verified trafficking of the therapeutic cells to sites at risk for FOP. These data provide proof-of-concept for the therapeutic utility of engineered cell therapy for the treatment of FOP. Significance statementIn this study, we describe our development of an autologous, closed-loop cell therapy which can migrate to sites of tissue injury and locally secreting an inhibitor of Activin A. Through our use of an Activin A-responsive promoter to drive expression of the recombinant Activin A inhibitor, this engineered cell therapy exhibits closed-loop behavior and effectively prevents heterotopic bone formation in a mouse model of fibrodysplasia ossificans progressiva (FOP). We believe that the findings in this manuscript impactful beyond FOP, and provide a blueprint for the development of marrow-derived cell therapies across the disease spectrum.

cell biology↗

bioRxiv2020

Translating the Human CANTAB Touchscreen Based Tasks to Evaluate Learning and Memory in Mouse Models of Down Syndrome

Humans with Down syndrome (DS) exhibit hippocampal learning deficits in the Cambridge Neuropsychological Test Automated Battery (CANTAB). Here we translated the CANTAB Visual Discrimination (VD) and Extinction tasks to investigate hippocampal learning and cortical inhibitory control in the Dp(16)1/Yey, Ts65Dn and Ts1Cje mouse models of DS. No food or water restriction was used prior to testing. The number of days to reach 70% correct answers and percent of correct responses were analyzed. All Dp(16)1/Yey, Ts1Cje and WT mice reached Stage 5 of pre-training. No differences between genotypes were found in percent of correct responses. Five Ts65Dn and one WT animals reached Stage 5 and only one Ts65Dn mouse reached VD. Ts1Cje mice took longer (17.86{+/-}3.19 days) to move to VD vs. WT (11.44{+/-}1.96 days, P=0.09). There were no differences between Dp(16)1/Yey and WT mice. At VD, the average percent of correct answers was significantly lower in Dp(16)1/Yey (22.70{+/-}1.93%) and Ts1Cje (34.39{+/-}1.98%) compared to WT littermates (32.18{+/-}1.49% and 41.11{+/-}1.45%, respectively, P<0.05). In another set of experiments, we demonstrated that mild food restriction significantly reduced the time needed to complete pre-training in C57BL/6J mice compared to C67BL/6J mice that had ad libitum access to food and water. In conclusion, we were able to apply human cognitive tests to evaluate hippocampal learning and cortical inhibitory control in three mouse models of DS. These studies demonstrate significant cognitive differences between strains. Future experiments will evaluate whether food restriction and/or pre- and postnatal therapy decreases the time intervals to achieve training mile.

animal behavior and cognition↗

bioRxiv2018

Apigenin as a Candidate Prenatal Treatment for Trisomy 21: Effects in Human Amniocytes and the Ts1Cje Mouse Model

Human fetuses with trisomy 21 (T21) have atypical brain development that is apparent sonographically in the second trimester. Prenatal diagnosis provides a potential opportunity to begin treatment in utero. We hypothesize that by analyzing and integrating dysregulated gene expression and pathways common to humans with DS and mouse models we can discover novel targets for therapy. Here, we tested the safety and efficacy of apigenin (4, 5, 7-trihydroxyflavone), identified using this approach, in both human amniocytes from fetuses with T21 and in the Ts1Cje mouse model. The experiments compared treated to untreated results in T21 and euploid cells, as well as in Ts1Cje mice and their wild-type littermate controls. T21 cells cultured with apigenin (2{micro}M) had significantly reduced oxidative stress and improved antioxidant defense response in vitro. Apigenin (333-400 mg/kg/day), mixed with chow, was initiated prenatally to the dams and fed to the pups over their lifetimes. There was no significant increase in birth defects or pup deaths resulting from prenatal apigenin treatment. Apigenin significantly improved several developmental milestones and spatial olfactory memory in Ts1Cje neonates. In addition, we noted sex-specific effects on exploratory behavior and long-term hippocampal memory in adult mice, with males showing significantly more improvement than females. Global gene expression analyses demonstrated that apigenin targets similar signaling pathways through common upstream regulators both in vitro and in vivo. These studies provide proof-of-principle that apigenin has therapeutic effects in preclinical models of Down syndrome.\n\nONE SENTENCE SUMMARYAs a candidate prenatal treatment for Down syndrome, apigenin improved oxidative stress/antioxidant capacity imbalance and reduced pathways associated with inflammation in human cells while improving aspects of behavior in the Ts1Cje mouse model.

genetics↗