Cyclic strain inhibits switching of smooth muscle cells to an osteoblastâ like phenotype

Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/154437/1/fsb2fj020459fje.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/154437/2/fsb2fj020459fje-sup-0001.pd

Using HSV-Thymidine Kinase for Safety in an Allogeneic Salivary Graft Cell Line

Extreme salivary hypofunction is a result of tissue damage caused by irradiation therapy for cancer in the head and neck region. Unfortunately, there is no currently satisfactory treatment for this condition that affects up to 40,000 people in the United States every year. As a novel approach to managing this problem, we are attempting to develop an orally implantable, fluid-secreting device (an artificial salivary gland). We are using the well-studied HSG salivary cell line as a potential allogeneic graft cell for this device. One drawback of using a cell line is the potential for malignant transformation. If such an untoward response occurred, the device could be removed. However, in the event that any HSG cells escaped, we wished to provide additional patient protection. Accordingly, we have engineered HSG cells with a hybrid adeno-retroviral vector, AdLTR.CMV-tk, to express the herpes simplex virus thymidine kinase (HSV-tk) suicide gene as a novel safety factor. Cells were grown on plastic plates or on poly-L-lactic acid disks and then transduced with different multiplicities of infection (MOIs) of the hybrid vector. Thereafter, various concentrations of ganciclovir (GCV) were added, and cell viability was tested. Transduced HSG cells expressed HSV-tk and were sensitive to GCV treatment. Maximal effects were seen at a MOI of 10 with 50 μM of GCV, achieving 95% cell killing on the poly-L-lactic acid substrate. These results suggest that engineering the expression of a suicide gene in an allogeneic graft cell may provide additional safety for use in an artificial salivary gland device.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/63119/1/10763270152436463.pd

Tissue Compatibility of Two Biodegradable Tubular Scaffolds Implanted Adjacent to Skin or Buccal Mucosa in Mice

Radiation therapy for cancer in the head and neck region leads to a marked loss of salivary gland parenchyma, resulting in a severe reduction of salivary secretions. Currently, there is no satisfactory treatment for these patients. To address this problem, we are using both tissue engineering and gene transfer principles to develop an orally implantable, artificial fluid-secreting device. In the present study, we examined the tissue compatibility of two biodegradable substrata potentially useful in fabricating such a device. We implanted in Balb/c mice tubular scaffolds of poly-L-lactic acid (PLLA), poly-glycolic acid coated with PLLA (PGA/PLLA), or nothing (sham-operated controls) either beneath the skin on the back, a site widely used in earlier toxicity and biocompatibility studies, or adjacent to the buccal mucosa, a site quite different functionally and immunologically. At 1, 3, 7, 14, and 28 days postimplantation, implant sites were examined histologically, and systemic responses were assessed by conventional clinical chemistry and hematology analyses. Inflammatory responses in the connective tissue were similar regardless of site or type of polymer implant used. However, inflammatory reactions were shorter and without epithelioid and giant cells in sham-operated controls. Also, biodegradation proceeded more slowly with the PLLA tubules than with the PGA/PLLA tubules. No significant changes in clinical chemistry and hematology were seen due to the implantation of tubular scaffolds. These results indicate that the tissue responses to PLLA and PGA/PLLA scaffolds are generally similar in areas subjacent to skin in the back and oral cavity. However, these studies also identified several potentially significant concerns that must be addressed prior to initiating any clinical applications of this device.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/63126/1/107632702760240562.pd

Diversity of the Human Skin Microbiome Early in Life

Within days after birth, rapid surface colonization of infant skin coincides with significant functional changes. Gradual maturation of skin function, structure, and composition continues throughout the first years of life. Recent reports have revealed topographical and temporal variations in the adult skin microbiome. Here we address the question of how the human skin microbiome develops early in life. We show that the composition of cutaneous microbial communities evolves over the first year of life, showing increasing diversity with age. Although early colonization is dominated by Staphylococci, their significant decline contributes to increased population evenness by the end of the first year. Similar to what has been shown in adults, the composition of infant skin microflora appears to be site specific. In contrast to adults, we find that Firmicutes predominate on infant skin. Timely and proper establishment of healthy skin microbiome during this early period might have a pivotal role in denying access to potentially infectious microbes and could affect microbiome composition and stability extending into adulthood. Bacterial communities contribute to the establishment of cutaneous homeostasis and modulate inflammatory responses. Early microbial colonization is therefore expected to critically affect the development of the skin immune function

The role of the extracellular matrix and mechanical strain on gene expression of engineered smooth muscle tissue.

The field of tissue engineering holds great promise for the treatment of cardiovascular disease. Cardiovascular tissues reside in a mechanically dynamic environment and it is therefore important to understand how vascular cells respond to mechanical signals from the extracellular matrix (ECM) to which they are adhered. The goal of this thesis is to provide a better understanding of the effects of mechanical strain on cardiovascular cell gene expression, particularly in terms of genes associated with the calcification process in the vasculature. Tissues were engineered by seeding smooth muscle cells (SMCs) into three-dimensional scaffolds. Mechanical strain was applied using a custom-made device to exert a uniaxial strain of 7% at a frequency of 1 Hz. SMCs utilized distinct integrin receptors to adhere to various substrates and cellular gene expression was regulated by the scaffold chemistry. These cells were found to express a variety of bone-associated genes, such as osteopontin, matrix gla protein (MGP), alkaline phosphatase, and the transcription factor CBFA-1. Strikingly, however, expression of these genes was downregulated in tissues exposed to cyclic strain at all time points ranging from 5 to 150 days. Further, long-term strain played a protective role against calcification, as unstrained tissues exhibited increased calcium deposition compared to strained tissues. The mechanism of strain-induced osteopontin and MGP gene expression by SMCs was also studied by investigating the involvement of the ECM and matrix-associated protein kinase (MAPK) signaling pathways. The MAPK signal transduction pathways ERK and p38 were studied and neither pathway regulated the expression of either osteopontin or MGP with strain application. However, blocking ERK signaling inhibited the expression of MGP, implicating the involvement of that pathway in the regulation of MGP expression. Overall, the results in this thesis suggest that without an appropriate mechanical environment, SMCs in three-dimensional culture undergo a phenotypic conversion to an osteoblast-like pattern of gene expression. These studies shed light onto how mechanical strain is transduced through the cell and regulates the gene expression of known mediators in the vascular calcification process. Understanding the role of strain in the vasculature can provide insight into causes of disease and lead to better treatment options.Ph.D.Applied SciencesBiological SciencesBiomedical engineeringCellular biologyUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttp://deepblue.lib.umich.edu/bitstream/2027.42/132710/2/3058026.pd

The Growth and Morphological Behavior of Salivary Epithelial Cells on Matrix Protein-Coated Biodegradable Substrata

The purpose of this study was to examine the growth and morphology of a salivary epithelial cell line (HSG) in vitro on several biodegradable substrata as an important step toward developing an artificial salivary gland. The substrates examined were poly-L-lactic acid (PLLA), polyglycolic acid (PGA), and two co-polymers, 85% and 50% PLGA, respectively. The substrates were formed into 20- to 25-mm disks, and the cells were seeded directly onto the polymers or onto polymers coated with specific extracellular matrix proteins. The two copolymer substrates became friable over time in aqueous media and proved not useful for these experiments. The purified matrix proteins examined included fibronectin (FN), laminin (LN), collagen I, collagen IV, and gelatin. In the absence of preadsorbed proteins, HSG cells did not attach to the polymer disks. The cells, in general, behaved similarly on both PLLA and PGA, although optimal results were obtained consistently in PLLA. On FN-coated PLLA disks, HSG cells were able to form a uniform monolayer, which was dependent on time and FN concentration. Coating of disks with LN, collagen I, and gelatin also promoted monolayer growth. This study defines the conditions necessary for establishing a monolayer organization of salivary epithelial cells with rapid proliferation on a biodegradable substrate useful for tissue engineering.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/63315/1/10763270050044380.pd

The impact of short-term predominate breastfeeding on cognitive outcome at 5 years

Aim: Breastfeeding is associated with IQ, school attendance and income. Despite the known benefits of breastfeeding, the rate of exclusive breastfeeding up to 6-months is low globally. We examined the effect of short-term breastfeeding on long-term IQ. Methods: In this secondary analysis of the prospective Cork BASELINE Birth Cohort Study, children were categorised as predominantly breastfed (n = 288) versus exclusively formula-fed (n = 254) at 2-months of age. Infants (n = 404) receiving mixed-feeding were excluded. Outcome was assessed using the KBIT II at 5-years. Multivariable linear regression was used to adjust for confounding variables. Results: Following adjustment for confounding variables, children, predominately breastfed at 2-months of age, demonstrated increased overall IQ (2.00 points (95% CI: 0.35 to 3.65) ; p = 0.018) and non-verbal IQ at 5-years of age (1.88 points (95% CI: 0.22 to 3.54); p = 0.027) compared to those never breastfed. No significant relationship was found with verbal IQ (p = 0.154). Conclusion: A significant increase in composite and non-verbal IQ at 5-years of age was associated with short-term breastfeeding. This study adds to a growing body of evidence that short-term breastfeeding promotes healthy cognitive development

Factors indicating intention to vaccinate with a COVID-19 vaccine among older U.S. adults.

BackgroundThe success of vaccination efforts to curb the COVID-19 pandemic will require broad public uptake of immunization and highlights the importance of understanding factors associated with willingness to receive a vaccine.MethodsU.S. adults aged 65 and older enrolled in the HeartlineTM clinical study were invited to complete a COVID-19 vaccine assessment through the HeartlineTM mobile application between November 6-20, 2020. Factors associated with willingness to receive a COVID-19 vaccine were evaluated using an ordered logistic regression as well as a Random Forest classification algorithm.ResultsAmong 9,106 study participants, 81.3% (n = 7402) responded and had available demographic data. The majority (91.3%) reported a willingness to be vaccinated. Factors most strongly associated with vaccine willingness were beliefs about the safety and efficacy of COVID-19 vaccines and vaccines in general. Women and Black or African American respondents reported lower willingness to vaccinate. Among those less willing to get vaccinated, 66.2% said that they would talk with their health provider before making a decision. During the study, positive results from the first COVID-19 vaccine outcome study were released; vaccine willingness increased after this report.ConclusionsEven among older adults at high-risk for COVID-19 complications who are participating in a longitudinal clinical study, 1 in 11 reported lack of willingness to receive COVID-19 vaccine in November 2020. Variability in vaccine willingness by gender, race, education, and income suggests the potential for uneven vaccine uptake. Education by health providers directed toward assuaging concerns about vaccine safety and efficacy can help improve vaccine acceptance among those less willing.Trial registrationClinicaltrials.gov NCT04276441