Biology subjects

Cooke, M. E.

Publications and source records attributed to Cooke, M. E..

4 recordsLinked to original sources

bioRxiv2024

Investigation of the Fasciola Cinereum, Absent in BTBR mice, and Comparison with the Hippocampal Area CA2

The arginine vasopressin 1b receptor (Avpr1b) plays an important role in social behaviors including social learning, memory, and aggression, and is known to be a specific marker for the cornu ammonis area 2 (CA2) regions of the hippocampus. The fasciola cinereum (FC) is an anatomical region in which Avpr1b expressing neurons are prominent, but the functional roles of the FC have yet to be investigated. Surprisingly, the FC is absent in the inbred BTBR T+tf/J (BTBR) mouse strain used to study core behavioral deficits of autism. Here, we characterized and compared transcriptomic expression profiles using single nucleus RNA sequencing and identified 7 different subpopulations and heterogeneity within the dorsal CA2 (dCA2) and FC. Mef2c, involved in autism spectrum disorder, is more highly expressed in the FC. Using Hiplex in situ hybridization, we examined the neuroanatomical locations of these subpopulations in the proximal and distal regions of the hippocampus. Anterograde tracing of Avpr1b neurons specific for the FC showed projections to the IG, dCA2, lacunosum molecular layer of CA1, dorsal fornix, septofibrial nuclei, and intermediate lateral septum (iLS). In contrast to the dCA2, inhibition of Avpr1b neurons in the FC by the inhibitory DREADD system during behavioral testing did not impair social memory. We performed single nucleus RNA sequencing in the dCA2 region and compared between wildtype (WT) and BTBR mice. We found that transcriptomic profiles of dCA2 neurons between BTBR and WT mice are very similar as they did not form any unique clusters; yet, we found there were differentially expressed genes between the dCA2s of BTBR and WT mice. Overall, this is a comprehensive study of the comparison of Avpr1b neuronal subpopulations between the FC and dCA2. The fact that FC is absent in BTBR mice, a mouse model for autism spectrum disorder, suggests that the FC may play a role in understanding neuropsychiatric disease.

neuroscience↗

bioRxiv2023

Stimulation of median raphe terminals in dorsal CA2 reduces social investigation in male mice specifically investigating social stimulus of ovariectomized female mice

The cornu ammonis area 2 (CA2) region is essential for social behaviors, especially in social aggression and social memory. Recently, we showed that targeted CA2 stimulation of vasopressin presynaptic fibers from the paraventricular nuclei of hypothalamus strongly enhances social memory in mice. In addition, the CA2 area of the mouse hippocampus receives neuronal inputs from other regions including the septal nuclei, the diagonal bands of Broca, supramammillary nuclei, and median raphe nucleus. However, the functions of these projections have been scarcely investigated. A functional role of median raphe (MR) - CA2 projection is supported by the MR to CA2 projections and 82% reduction of hippocampal serotonin (5-HT) levels following MR lesions. Thus, we investigated the behavioral role of presynaptic fibers from the median raphe nucleus projecting to the dorsal CA2 (dCA2). Here, we demonstrate the optogenetic stimulation of 5-HT projections to dCA2 from the MR do not alter social memory, but instead reduce social interaction. We show that optical stimulation of MR fibers excites interneurons in the stratum radiatum (SR) and stratum lacunosum moleculare (SLM) of CA2 region. Consistent with these observations, we show that bath application of 5-HT increases spontaneous GABA release onto CA2 pyramidal neurons and excites presumed interneurons located in the SR/SLM. This is the first study, to our knowledge, which investigates the direct effect of 5-HT release from terminals onto dCA2 neurons on social behaviors. This highlights the different roles for these inputs (i.e., vasopressin inputs regulating social memory versus serotonin inputs regulating social interaction).

neuroscience↗

bioRxiv2023

Nanoparticle-Functionalized Acrylic Bone Cement for Local Therapeutic Delivery to Spinal Metastases

Polymethylmethacrylate bone cement is often used to reconstruct critical-sized defects generated by surgical resection of spinal metastases. Residual tumor cells after a resection can drive recurrence and destabilization. Doxorubicin (DOX) is a common chemotherapeutic drug with unwanted side-effects when administered systemically. Mesoporous silica nanoparticles are gaining attention for targeted drug delivery to bypass the negative side effects associated with systemic drug administration. We developed a nanoparticle-functionalized cement for the local release of DOX and tested its ability to suppress cancer cells. DOX was loaded onto nanoparticles which were then mixed into the cement. Drug release profiles were obtained over a period of 4 weeks. Cement constructs were incubated with 2D and 3D cultures of breast and prostate cancer cell lines, and cell metabolic activity and viability were evaluated. Cell migration and spheroid growth were assessed in collagen-coated spheroid cultures. Nanoparticles were homogenously dispersed and did not alter cement mechanical strength. A sustained DOX release profile was achieved with the addition of nanoparticles to the bone cement. The release profile of DOX from nanoparticle cement may be modified by varying the amount of the drug loaded onto the nanoparticles and the proportion of nanoparticles in the cement. Cells treated with the cement constructs showed a dose- and time-dependent inhibition. Cell migration and spheroid growth were impaired in 3D culture. We show that nanoparticles are essential for sustained DOX release from bone cement. DOX-loaded nanoparticle cement can inhibit cancer cells and impair their migration, with strong potential for in vivo translation studies.

bioengineering↗

bioRxiv2022

Continuous two-phase in vitro co-culture model of the enthesis

The enthesis is the interfacial tissue between ligament or tendon, and bone, which connects tissues of distinctly different mechanical properties. Although ligament and enthesis injury is commonplace, the development and healing mechanisms of these tissues are yet unclear. Current models for investigating these mechanisms are primarily in vivo animal models as in vitro models have been limited. In this study, an in vitro enthesis model was developed using a modified gel aspiration-ejection (GAE) method. Continuous two-phase aligned dense collagen (ADC) hydrogels with an overlapping interface were fabricated within 2 hours. The mechanical properties of acellular two-phase ADC confirmed the continuous nature of this model, as the mechanical properties showed no significant difference compared to single-phase ADC and maintained comparable structural and mechanical characteristics of immature ligaments and unmineralized bone. Human anterior cruciate ligament (ACL) fibroblasts and human spine vertebral osteoblasts were isolated from donor tissues and were seeded to form the enthesis model. These were cultured for 14 days, at which the viability and proliferation was observed to be 85 {+/-} 7.5% and 230 {+/-} 52%, respectively. Histological and immunofluorescence analyses at day 14 revealed extensive cell-driven matrix remodelling, and the seeded fibroblasts and osteoblasts maintained their phenotype within their compartments of the layered co-culture model. These results demonstrate the rapid fabrication of a two-phase co-culture system that can be utilized as an in vitro model to further understand the degenerative and regenerative mechanisms within the enthesis.

bioengineering↗