Academic Appointments

  • Basic Life Research Scientist, Bioengineering

Contact

Additional Info

  • Mail Code: 5444

All Publications

  • Amplifying Endoplasmic Reticulum Stress With Adenosine Triphosphate-Coated Gold Nanoclusters: A Promising Approach for the Treatment of Vestibular Schwannoma. Otology & neurotology : official publication of the American Otological Society, American Neurotology Society [and] European Academy of Otology and Neurotology Kullar, P. J., Bekale, L. A., Chen, J., Duggaraju, R., Tun, Z. M., Parr, F., Hedrick, M. L., Schiel, V., Vasilijic, S., Stankovic, K. M., Santa Maria, P. L. 2025; 46 (7): e269-e277

    Abstract

    We hypothesize that gold nanoclusters functionalized with adenosine triphosphate (AuNC@ATP) can inhibit schwannoma growth.There is an unmet need for an effective pharmacotherapy to treat vestibular schwannoma (VS) that does not carry the risk profile of current therapeutic modalities. Our previous research demonstrated that AuNC@ATP displays antimicrobial properties through its ability to induce a stress response, resulting in unfolded protein accumulation in the periplasm. The accumulation of unfolded proteins in the endoplasmic reticulum (ER) can trigger ER stress, activating the unfolded protein response (UPR). ER stress has been shown to inhibit tumor growth and activate apoptotic pathways. We therefore sought to determine whether AuNC@ATP could enhance ER stress and inhibit schwannoma growth in vitro.Rat schwannoma (S16) cells were utilized as a cellular model. The growth ability of schwannoma cells in the absence and presence of a sublethal dose of AuNC@ATP was compared to establish the inhibitory activity of this ER stress inducer. The ability of AuNC@ATP to induce ER stress was measured using thioflavin T (Th-T) fluorescence. Unfolded protein imaging was performed using TPE-MI, and apoptosis was interrogated using the Caspase-Glo 3/7 Assay. Human VS cells were isolated from tumor samples of three different VS patients. Cytoxicity of gold nanocluster treated cells was assessed using CellTox Green Dye and metabolic activity by MTT assay.The addition of AuNC@ATP to S16 cells for 24 hours resulted in a concentration-dependent decrease in cell viability, with a substantial loss observed at a concentration of 27.93 μM, reaching 95%. Subsequently, S16 cells were cultured in a medium containing a sublethal concentration of AuNC@ATP (6.98 μM). After 96 hours, the cell count reached 107 without AuNC@ATP compared with 105 with it. Additionally, the antitumor activity of AuNC@ATP appears to be mediated through amplified ER stress as evidenced by Th-T fluorescence and accumulation of unfolded proteins in the ER as evidenced by TPE-MI fluorescence. In addition, AuNC@ATP caused cell death of human VS cells in a concentration-dependent manner and almost totally abolished metabolic activity of treated cells.Our study suggests that using a nano-drug capable of inducing ER stress responses could be a promising strategy for reducing schwannoma growth.

    View details for DOI 10.1097/MAO.0000000000004403

    View details for PubMedID 40644638

  • Localized application of SAG21k-loaded fibrin hydrogels for targeted modulation of the hedgehog pathway in facial nerve injury. International journal of biological macromolecules He, L., Sato, J. E., Sundar, P., Azimi, T., Beachy, P. A., Bekale, L. A., Pepper, J. P. 2024: 131747

    Abstract

    Given the broad biological effects of the Hedgehog (Hh) pathway, there is potential clinical value in local application of Hh pathway modulators to restrict pathway activation of target tissues and avoid systemic pathway activation. One option to limit Hh pathway activation is using fibrin hydrogels to deliver pathway modulators directly to tissues of interest, bypassing systemic distribution of the drug. In this study, we loaded the potent Hh pathway agonist, SAG21k, into fibrin hydrogels. We describe the binding between fibrin and SAG21k and achieve sustained release of the drug in vitro. SAG21k-loaded fibrin hydrogels exhibit strong biological activity in vitro, using a pathway-specific reporter cell line. To test in vivo activity, we used a mouse model of facial nerve injury. Application of fibrin hydrogels is a common adjunct to surgical nerve repair, and the Hh pathway is known to play an important role in facial nerve injury and regeneration. Local application of the Hh pathway agonist SAG21k using a fibrin hydrogel applied to the site of facial nerve injury successfully activates the Hh pathway in treated nerve tissue. Importantly, this method appears to avoid systemic pathway activation when Hh-responsive organs are analyzed for transcriptional pathway activation. This method of local tissue Hh pathway agonist administration allows for effective pathway targeting surgically accessible tissues and may have translational value in situations where supranormal pathway activation is therapeutic.

    View details for DOI 10.1016/j.ijbiomac.2024.131747

    View details for PubMedID 38670196

  • A novel mouse model of chronic suppurative otitis media and its use in preclinical antibiotic evaluation. Science advances Khomtchouk, K. M., Kouhi, A. n., Xia, A. n., Bekale, L. A., Massa, S. M., Sweere, J. M., Pletzer, D. n., Hancock, R. E., Bollyky, P. L., Santa Maria, P. L. 2020; 6 (33): eabc1828

    Abstract

    Chronic suppurative otitis media (CSOM) is a neglected pediatric disease affecting 330 million worldwide for which no new drugs have been introduced for over a decade. We developed a mouse model with utility in preclinical drug evaluation and antimicrobial discovery. Our model used immune-competent mice, tympanic membrane perforation and inoculation with luminescent Pseudomonas aeruginosa that enabled bacterial abundance tracking in real-time for 100 days. The resulting chronic infection exhibited hallmark features of clinical CSOM, including inhibition of tympanic membrane healing and purulent ear discharge. We evaluated the standard care fluoroquinolone ofloxacin and demonstrated that this therapy resulted in a temporary reduction of bacterial burden. These data are consistent with the clinical problem of persistent infection in CSOM and the need for therapeutic outcome measures that assess eradication post-therapeutic endpoint. We conclude that this novel mouse model of CSOM has value in investigating new potential therapies.

    View details for DOI 10.1126/sciadv.abc1828

    View details for PubMedID 32851190

    View details for PubMedCentralID PMC7428333