Department of Biomedical Engineering Works
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Item Finite Element Analysis as an Iterative Design Tool for Students in an Introductory Biomechanics Course(ASME, 2021-12) Higbee, Steven; Miller, Sharon; Biomedical Engineering, School of Engineering and TechnologyInsufficient engineering analysis is a common weakness of student capstone design projects. Efforts made earlier in a curriculum to introduce analysis techniques should improve student confidence in applying these important skills toward design. To address student shortcomings in design, we implemented a new design project assignment for second-year undergraduate biomedical engineering students. The project involves the iterative design of a fracture fixation plate and is part of a broader effort to integrate relevant hands-on projects throughout our curriculum. Students are tasked with (1) using computer-aided design (CAD) software to make design changes to a fixation plate, (2) creating and executing finite element models to assess performance after each change, (3) iterating through three design changes, and (4) performing mechanical testing of the final device to verify model results. Quantitative and qualitative methods were used to assess student knowledge, confidence, and achievement in design. Students exhibited design knowledge gains and cognizance of prior coursework knowledge integration into their designs. Further, student's self-reported confidence gains in approaching design, working with hardware and software, and communicating results. Finally, student self-assessments exceeded instructor assessment of student design reports, indicating that students have significant room for growth as they progress through the curriculum. Beyond the gains observed in design knowledge, confidence, and achievement, the fracture fixation project described here builds student experience with CAD, finite element analysis, three-dimensional printing, mechanical testing, and design communication. These skills contribute to the growing toolbox that students ultimately bring to capstone design.Item The Effect of Single Versus Group μCT on the Detection of Trabecular and Cortical Disease Phenotypes in Mouse Bones(Wiley, 2021-03-05) Kohler, Rachel; Tastad, Carli A.; Stacy, Alexander J.; Swallow, Elizabeth A.; Metzger, Corinne E.; Allen, Matthew R.; Wallace, Joseph M.; Biomedical Engineering, School of Engineering and TechnologyMicro‐computed tomography is a critical assessment tool for bone‐related preclinical research, especially in murine models. To expedite the scanning process, researchers often image multiple bones simultaneously; however, it is unknown if this impacts scan quality and alters the ability to detect differences between experimental groups. The purpose of this study was to assess the effect of multibone scanning on detecting disease‐induced changes in bone microarchitecture and mineral density by group scanning two murine models with known skeletal defects: the Col1a2 G610C/+ model of osteogenesis imperfecta and an adenine‐induced model of chronic kidney disease. Adult male femurs were scanned individually and in random groups of three and eight in a Bruker Skyscan 1172 and 1176, respectively, then assessed for standard trabecular and cortical bone measures. Although scanning methodology altered raw values, with trabecular microarchitecture values more affected than cortical properties, a disease phenotype was still detectable in both group and solo scans. However, tissue mineral density in both trabecular and cortical bone was significantly impacted by group versus solo scanning. Researchers may be able to use small groupings in a single μCT scan to expedite preclinical analyses when the overall bone phenotype is large to decrease costs and increase speed of discoveries; however the details of scanning (single or group) should always be reported.Item Preventing tumor progression to the bone by induced tumor-suppressing MSCs(Ivyspring International, 2021-03-05) Sun, Xun; Li, Kexin; Zha, Rongrong; Liu, Shengzhi; Fan, Yao; Wu, Di; Hase, Misato; Aryal, Uma K.; Lin, Chien-Chi; Li, Bai-Yan; Yokota, Hiroki; Biomedical Engineering, School of Engineering and TechnologyBackground: Advanced breast cancer metastasizes to many organs including bone, but few effective treatments are available. Here we report that induced tumor-suppressing (iTS) MSCs protected bone from metastases while un-induced MSCs did not. Methods: iTS MSCs were generated by overexpressing Lrp5, β-catenin, Snail, or Akt. Their tumor-suppressing capability was tested using a mouse model of mammary tumors and bone metastasis, human breast cancer tissues and cancer cell lines. Results: In a mouse model, the induced MSC-derived conditioned medium (MSC CM) reduced mammary tumors and suppressed tumor-induced osteolysis. Tumor-promoting genes such as CXCL2 and LIF, as well as PDL1, a blocker of T-cell-based immune responses were downregulated. Proteomics analysis revealed that heat shock protein 90 (Hsp90ab1), calreticulin (Calr) and peptidylprolyl isomerase B (Ppib), which are highly expressed intracellular proteins in many cancers, were enriched in MSC CM as atypical tumor suppressors. Thus, overexpressing selected genes that were otherwise tumorigenic rendered MSCs the tumor-suppressing capability through the atypical suppressors, as well as p53 and Trail. Notably, the inhibitory effect of Lrp5- and Akt-overexpressing MSC CMs, Hsp90ab1 and Calr presented selective inhibition to tumor cells than non-tumor cells. The development of bone-resorbing osteoclasts was also suppressed by MSC CMs. Conclusion: Collectively, the results showed an anti-tumor effect of iTS MSCs and suggested novel therapeutic approaches to suppress the progression of tumors into the bone.Item Engineering Tools for Regulating Hypoxia in Tumour Models(Wiley, 2021) Kim, Min Hee; Green, Steven D.; Lin, Chien-Chi; Konig, Heiko; Biomedical Engineering, School of Engineering and TechnologyMajor advances in the field of genomic technologies have led to an improvement in cancer diagnosis, classification and prognostication. However, many cancers remain incurable due to the development of drug resistance, minimal residual disease (MRD) and disease relapse, highlighting an incomplete understanding of the mechanisms underlying these processes. In recent years, the impact of non-genetic factors on neoplastic transformations has increasingly been acknowledged, and growing evidence suggests that low oxygen (O2) levels (ie hypoxia) in the tumour microenvironment play a critical role in the development and treatment of cancer. As a result, there is a growing need to develop research tools capable of reproducing physiologically relevant O2 conditions encountered by cancer cells in their natural environments in order to gain in-depth insight into tumour cell metabolism and function. In this review, the authors highlight the importance of hypoxia in the pathogenesis of malignant diseases and provide an overview of novel engineering tools that have the potential to further drive this evolving, yet technically challenging, field of cancer research.Item Hydrogel Models with Stiffness Gradients for Interrogating Pancreatic Cancer Cell Fate(MDPI, 2021-03) Chang, Chun-Yi; Lin, Chien-Chi; Biomedical Engineering, School of Engineering and TechnologyPancreatic ductal adenocarcinoma (PDAC) is the most common type of pancreatic cancer and has seen only modest improvements in patient survival rate over the past few decades. PDAC is highly aggressive and resistant to chemotherapy, owing to the presence of a dense and hypovascularized fibrotic tissue, which is composed of stromal cells and extracellular matrices. Increase deposition and crosslinking of matrices by stromal cells lead to a heterogeneous microenvironment that aids in PDAC development. In the past decade, various hydrogel-based, in vitro tumor models have been developed to mimic and recapitulate aspects of the tumor microenvironment in PDAC. Advances in hydrogel chemistry and engineering should provide a venue for discovering new insights regarding how matrix properties govern PDAC cell growth, migration, invasion, and drug resistance. These engineered hydrogels are ideal for understanding how variation in matrix properties contributes to the progressiveness of cancer cells, including durotaxis, the directional migration of cells in response to a stiffness gradient. This review surveys the various hydrogel-based, in vitro tumor models and the methods to generate gradient stiffness for studying migration and other cancer cell fate processes in PDAC.Item Hydrogel Models with Stiffness Gradients for Interrogating Pancreatic Cancer Cell Fate(MDPI, 2021-03-13) Chang, Chun-Yi; Lin, Chien-Chi; Biomedical Engineering, School of Engineering and TechnologyPancreatic ductal adenocarcinoma (PDAC) is the most common type of pancreatic cancer and has seen only modest improvements in patient survival rate over the past few decades. PDAC is highly aggressive and resistant to chemotherapy, owing to the presence of a dense and hypovascularized fibrotic tissue, which is composed of stromal cells and extracellular matrices. Increase deposition and crosslinking of matrices by stromal cells lead to a heterogeneous microenvironment that aids in PDAC development. In the past decade, various hydrogel-based, in vitro tumor models have been developed to mimic and recapitulate aspects of the tumor microenvironment in PDAC. Advances in hydrogel chemistry and engineering should provide a venue for discovering new insights regarding how matrix properties govern PDAC cell growth, migration, invasion, and drug resistance. These engineered hydrogels are ideal for understanding how variation in matrix properties contributes to the progressiveness of cancer cells, including durotaxis, the directional migration of cells in response to a stiffness gradient. This review surveys the various hydrogel-based, in vitro tumor models and the methods to generate gradient stiffness for studying migration and other cancer cell fate processes in PDAC.Item Inhibition of the Growth of Breast Cancer-Associated Brain Tumors by the Osteocyte-Derived Conditioned Medium(MDPI, 2021-03-03) Sano, Tomohiko; Sun, Xun; Feng, Yan; Liu, Shengzhi; Hase, Misato; Fan, Yao; Zha, Rongrong; Wu, Di; Aryal, Uma K.; Li, Bai-Yan; Sudo, Akihiro; Yokota, Hiroki; Biomedical Engineering, School of Engineering and TechnologyThe brain is a common site of metastasis from advanced breast cancer but few effective treatments are available. We examined a therapeutic option with a conditioned medium (CM), focusing on the role of Lrp5 and β-catenin in Wnt signaling, and IL1ra in osteocytes. Osteocytes presented the innate anti-tumor effect and the overexpression of the above genes strengthened their action. In a mouse model, the injection of their CM inhibited mammary tumors and tumor-driven osteolysis. Importantly, Lrp5- and/or IL1ra-overexpressing osteocytes or the local administration of β-catenin-overexpressing CM markedly inhibited brain tumors. In the transport analysis, tumor-suppressing factors in CM were shown to diffuse through the skull. Mechanistically, the CM with overexpression of the above genes downregulated oncogenic genes such as MMP9, Runx2, TGFβ, and Snail in breast cancer cells. Also, the CM with β-catenin overexpression downregulated CXCL1 and CXCL5 and upregulated tumor suppressors such as LIMA1, DSP, p53, and TRAIL in breast cancer cells. Notably, whole-genome proteomics revealed that histone H4 was enriched in CM and acted as an atypical tumor suppressor. Lrp5-overexpressing MSCs were also shown to act as anti-tumor agents. Collectively, this study demonstrated the therapeutic role of engineered CM in brain tumors and the tumor-suppressing action of extracellular histone H4. The result sheds light on the potential CM-based therapy for breast cancer-associated brain metastases in a minimally invasive manner.Item Knee loading repairs osteoporotic osteoarthritis by relieving abnormal remodeling of subchondral bone via Wnt/β-catenin signaling(Wiley, 2020-02) Zheng, Weiwei; Ding, Beibei; Li, Xinle; Liu, Daquan; Yokota, Hiroki; Zhang, Ping; Biomedical Engineering, School of Engineering and TechnologyOsteoporotic osteoarthritis (OPOA) is a common bone disease mostly in the elderly, but the relationship between Osteoporotic (OP) and osteoarthritis (OA) is complex. It has been shown that knee loading can mitigate OA symptoms. However, its effects on OPOA remain unclear. In this study, we characterized pathological linkage of OP to OA, and evaluated the effect of knee loading on OPOA. We employed two mouse models (OA and OPOA), and conducted histology, cytology, and molecular analyses. In the OA and OPOA groups, articular cartilage was degenerated and Osteoarthritis Research Society International score was increased. Subchondral bone underwent abnormal remodeling, the differentiation of bone marrow mesenchymal stem cells (BMSCs) to osteoblasts and chondrocytes was reduced, and migration and adhesion of pre-osteoclasts were enhanced. Compared to the OA group, the pathological changes of OA in the OPOA group were considerably aggravated. After knee loading, however, cartilage degradation was effectively prevented, and the abnormal remodeling of subchondral bone was significantly inhibited. The differentiation of BMSCs was also improved, and the expression of Wnt/β-catenin was elevated. Collectively, this study demonstrates that osteoporosis aggravates OA symptoms. Knee loading restores OPOA by regulating subchondral bone remodeling, and may provide an effective method for repairing OPOA.Item Suppression of sost/sclerostin and dikkopf-1 augment intervertebral disc structure in mice(Wiley, 2022) Kroon, Tori; Bhadouria, Neharika; Niziolek, Paul; Edwards, Daniel; Clinkenbeard, Erica L.; Robling, Alexander; Holguin, Nilsson; Biomedical Engineering, School of Engineering and TechnologyIntervertebral disc (IVD) degeneration is a leading cause of low back pain, characterized by accelerated extracellular matrix breakdown and IVD height loss but there is no approved pharmacological therapeutic. Deletion of Wnt ligand competitor Lrp5 induces IVD degeneration, suggesting that Wnt signaling is essential for IVD homeostasis. Therefore, the IVD may respond to neutralization of Wnt ligand competitors sost(gene)/sclerostin(protein) and/or dikkopf-1 (dkk1). Anti-sclerostin antibody (scl-Ab) is an FDA-approved bone therapeutic that activates Wnt signaling. We (1) determined if pharmacological neutralization of sclerostin, dkk1 or their combination would stimulate Wnt signaling and augment IVD structure and (2) determined the prolonged adaptation of the IVD to global, persistent deletion of sost. Nine-week-old C57Bl/6J female mice (n = 6-7/grp) were subcutaneously injected 2x/wk for 5.5 wk with scl-Ab (25 mg/kg), dkk1-Ab (25 mg/kg), 3:1 scl-Ab/dkk1-Ab (18.75:6.25 mg/kg) or vehicle (veh). Separately, IVD of sost KO and wildtype (WT) mice (n = 8/grp) were harvested at 16 weeks of age. First, compared to vehicle, injection of scl-Ab, dkk1-Ab and 3:1 scl-Ab/dkk1-Ab similarly increased lumbar IVD height and β-catenin gene expression. Despite these similarities, only injection of scl-Ab alone strengthened IVD mechanical properties and decreased heat shock protein gene expressions. Genetically and compared to WT, sost KO enlarged IVD height, increased proteoglycan staining and imbibed IVD hydration. Notably, persistent deletion of sost was compensated by upregulation of dkk1, which consequently reduced the cell nuclear fraction for Wnt signaling co-transcription factor β-catenin in the IVD. Lastly, RNA-sequencing pathway analysis confirmed the compensatory suppression of Wnt signaling and revealed a reduction of cellular stress-related pathways. Together, suppression of sost/sclerostin or dkk1 each augmented IVD structure by stimulating Wnt signaling, but scl-Ab outperformed dkk1-Ab in strengthening the IVD. Ultimately, postmenopausal women prescribed scl-Ab injections to prevent vertebral fracture may also benefit from a restoration of IVD height and health.Item Loading-induced antitumor capability of murine and human urine(Wiley, 2020-06) Wu, Di; Fan, Yao; Liu, Shengzhi; Woollam, Mark D.; Sun, Xun; Murao, Eiji; Zha, Rongrong; Prakash, Rahul; Park, Charles; Siegel, Amanda P.; Liu, Jing; Agarwal, Mangilal; Li, Bai-Yan; Yokota, Hiroki; Biomedical Engineering, School of Engineering and TechnologyWhile urine has been considered as a useful bio-fluid for health monitoring, its dynamic changes to physical activity are not well understood. We examined urine's possible antitumor capability in response to medium-level, loading-driven physical activity. Urine was collected from mice subjected to 5-minute skeletal loading and human individuals before and after 30-minute step aerobics. Six cancer cell lines (breast, prostate, and pancreas) and a mouse model of the mammary tumor were employed to evaluate the effect of urine. Compared to urine collected prior to loading, urine collected post-activity decreased the cellular viability, proliferation, migration, and invasion of tumor cells, as well as tumor weight in the mammary fat pad. Detection of urinary volatile organic compounds and ELISA assays showed that the loading-conditioned urine reduced cholesterol and elevated dopamine and melatonin. Immunohistochemical fluorescent images presented upregulation of the rate-limiting enzymes for the production of dopamine and melatonin in the brain. Molecular analysis revealed that the antitumor effect was linked to the reduction in molecular vinculin-linked molecular force as well as the downregulation of the Lrp5-CSF1-CD105 regulatory axis. Notably, the survival rate for the high expression levels of Lrp5, CSF1, and CD105 in tumor tissues was significantly lowered in the Cancer Genome Atlas database. Collectively, this study revealed that 5- or 10-minute loading-driven physical activity was sufficient to induce the striking antitumor effect by activating the neuronal signaling and repressing cholesterol synthesis. The result supported the dual role of loading-conditioned urine as a potential tumor suppressor and a source of diagnostic biomarkers.