Synthetic symmetry breaking and programmable multicellular structure formation

During development, cells undergo symmetry breaking into differentiated subpopulations that self-organize into complex structures.1,2,3,4,5 However, few tools exist to recapitulate these behaviors in a controllable and coupled manner.6,7,8,9 Here, we engineer a stochastic recombinase genetic switch tunable by small molecules to induce programmable symmetry breaking, commitment to downstream cell fates, and morphological self-organization. Inducers determine commitment probabilities, generating tunable subpopulations as a function of inducer dosage. We use this switch to control the cell-cell adhesion properties of cells committed to each fate.10,11 We generate a wide variety of 3D morphologies from a monoclonal population and develop a computational model showing high concordance with experimental results, yielding new quantitative insights into the relationship between cell-cell adhesion strengths and downstream morphologies. We expect that programmable symmetry breaking, generating precise and tunable subpopulation ratios and coupled to structure formation, will serve as an integral component of the toolbox for complex tissue and organoid engineering.

979. Disparities in PrEP uptake and adherence among cisgender women using a pharmacologic measure

Background

HIV pre-exposure prophylaxis (PrEP) is 99% effective at preventing new HIV infections if taken daily. To be successful, PrEP requires concurrent efforts to optimize uptake, persistence, and adherence.

In 2018, cisgender (cis) women accounted for 19% of new HIV infections in the US but comprised only 7% of all PrEP users. Studies show poor PrEP adherence amongst cis women, but there is a paucity of real-world clinical data describing PrEP adherence among cis women and gender minority people.

Methods

An adherence test that measures the concentration of tenofovir in urine samples using a liquid chromatography mass spectrometry (LC-MS/MS) was used to assess recent PrEP adherence at 8 clinics. Urine samples were collected during routine visits and analyzed using the LC-MS/MS assay. Test results were retrospectively paired with gender data, when available, and sex assigned at birth (SAAB) data. Adherence data were aggregated and analyzed to assess non-adherence proportions by sub-population.

Results

Gender data were available from 1,461 patients at 5 clinics, 1,344 (92%) of whom were cis males (Figure 1).

From the 5 clinics where gender and SAAB data were available, 3,835 tests were conducted and 517 (13.5%) indicated non-adherence (Figure 2).

3 additional clinics conduct routine adherence testing and collect SAAB data (gender data not available). At these 8 clinics, SAAB data were available for 2,773 PrEP patients, totaling 5,602 urine tests (Figure 3).

Among these 5,602 adherence tests, 813 (14.5%) indicated non-adherence (Figure 4). SAAB females demonstrated significantly higher non-adherence than SAAB males (22% vs 14%, p< 0.001).

Across clinics, 89%-98% of PrEP patients are SAAB male (Figure 5).

Within these 8 clinics, SAAB female demonstrated consistently higher non-adherence (17%-44%, vs 12%-17% for SAAB males) (Figure 6).

Figures 1 and 2

Figures 3 and 4

Figures 5 and 6

Conclusion

Real-world data align with nationwide trends in PrEP utilization and show that the majority of PrEP patients are cis men. When initiated on PrEP, cis women exhibit higher rates of non-adherence than cis men. These data underscore the need to collect gender-identity data to monitor PrEP disparities and suggest that greater efforts are needed to target PrEP access, utilization, and accompanying support services to cis women and gender minority groups.

Disclosures

All Authors: No reported disclosures

A high-throughput screening and computation platform for identifying synthetic promoters with enhanced cell-state specificity (SPECS)

Cell state-specific promoters constitute essential tools for basic research and biotechnology because they activate gene expression only under certain biological conditions. Synthetic Promoters with Enhanced Cell-State Specificity (SPECS) can be superior to native ones, but the design of such promoters is challenging and frequently requires gene regulation or transcriptome knowledge that is not readily available. Here, to overcome this challenge, we use a next-generation sequencing approach combined with machine learning to screen a synthetic promoter library with 6107 designs for high-performance SPECS for potentially any cell state. We demonstrate the identification of multiple SPECS that exhibit distinct spatiotemporal activity during the programmed differentiation of induced pluripotent stem cells (iPSCs), as well as SPECS for breast cancer and glioblastoma stem-like cells. We anticipate that this approach could be used to create SPECS for gene therapies that are activated in specific cell states, as well as to study natural transcriptional regulatory networks.

DNAplotlib: Programmable Visualization of Genetic Designs and Associated Data

DNAplotlib ( www.dnaplotlib.org ) is a computational toolkit for the programmable visualization of highly customizable, standards-compliant genetic designs. Functions are provided to aid with both visualization tasks and to extract and overlay associated experimental data. High-quality output is produced in the form of vector-based PDFs, rasterized images, and animated movies. All aspects of the rendering process can be easily customized or extended by the user to cover new forms of genetic part or regulation. DNAplotlib supports improved communication of genetic design information and offers new avenues for static, interactive and dynamic visualizations that map and explore the links between the structure and function of genetic parts, devices and systems; including metabolic pathways and genetic circuits. DNAplotlib is cross-platform software developed using Python.

Demarcation of secondary hyperalgesia zones: Punctate stimulation pressure matters

BACKGROUND

Secondary hyperalgesia is increased sensitivity in normal tissue near an injury, and it is a measure of central sensitization reflecting injury-related effects on the CNS. Secondary hyperalgesia areas (SHAs), usually assessed by polyamide monofilaments, are important outcomes in studies of analgesic drug effects in humans. However, since the methods applied in demarcating the secondary hyperalgesia zone seem inconsistent across studies, we examined the effect of a standardized approach upon the measurement of SHA following a first degree burn injury (BI).

NEW METHOD

The study was a two-observer, test-retest study with the two sessions separated by 6wk. An observer-blinded design adjusted to examine day-to-day and observer-to-observer variability in SHA was used. In 23 healthy volunteers (12 females/11 males) a BI was induced by a contact thermode (47.0°C, 420s, 2.5×5.0cm(2)). The SHA, demarcated by polyamide monofilaments (bending force: 0.2, 69 and 2569mN) and a "weighted-pin" stimulator (512mN), were assessed 45 to 75min after each BI.

RESULTS

A random effect, linear mixed model demonstrated a logarithmic correlation between elicited skin pressures (mN/mm(2)) and the SHAs (P<0.0001). No day-to-day or observer-to-observer differences in SHAs were observed. Intraclass correlation coefficients, in the range of 0.51 to 0.84, indicated a moderate to almost perfect reliability between observers.

COMPARISON WITH EXISTING METHODS

No standardized approach in SHA-assessment has hitherto been presented.

CONCLUSIONS

This is the first study to demonstrate that demarcation of secondary hyperalgesia zones depends on the developed pressure of the punctate stimulator used.