Voided Volume for Assessment of Bladder Emptying After Female Pelvic Floor Surgery: A Randomized Controlled Trial.

IMPORTANCE: To study alternative voiding trial (VT) methods after urogynecologic surgery that may potentially decrease catheterization. OBJECTIVE: The aim of the study is to compare voiding assessment based on a minimum spontaneous voided volume of 150 mL with the standard retrograde fill (RF) approach in women after urogynecologic procedures. STUDY DESIGN: Women undergoing urogynecologic surgery were randomized to RF or spontaneous void (SV) groups. Women in the RF group had their bladders backfilled with 300 mL of saline before catheter removal, those in the SV group did not. To pass the VT, patients in the RF group were required to void 150 mL at one time within 60 minutes, and patients in the SV group had to do the same within 6 hours. The primary outcome was the VT failure rate. We also compared the false pass rate, urinary tract infections, satisfaction, and preference of VT method. RESULTS: One hundred nine women were enrolled in the study, 54 had SV and 55 underwent RF. Baseline characteristics were not significantly different other than history of prior hysterectomy. There was no significant difference in procedures between the groups. There was no difference in VT failure rate between the groups-SV (7.4%) and RF (12.7%, P = 0.39). The false pass rate was 0 in each group. Urinary tract infection rates were similar between SV (14.8%) and RF (14.5%) groups ( P = 0.34). Patient satisfaction for VT method was not significantly different. CONCLUSIONS: Spontaneous VT was not superior to retrograde void trial. Therefore, we cannot recommend one method of VT after urogynecologic surgery.CondensationVoiding assessment based on minimum SV of 150 mL is comparable with VT with RF after surgeries for prolapse and urinary incontinence.

Bladder urothelial BK channel activity is a critical mediator for innate immune response in urinary tract infection pathogenesis.

The open probability of calcium-activated voltage-gated potassium channel (BK channel) on bladder umbrella urothelial cells is increased by lipopolysaccharide (LPS). It is hypothesized that this channel's activity is important in the urothelial innate immune response during urinary tract infection (UTI). We performed in vivo studies using female C57BL/6 mice whose bladders were inoculated with LPS (150 µl of 1 mg/ml) or uropathogenic Escherichia coli (UPEC, UTI89), without and with intravesical BK inhibitor iberiotoxin (IBTX, 1 µM). Inflammatory biomarkers (chemokines and cytokines) were measured in urine specimens collected 2 h after inoculation using a 32-multiplex ELISA. Of these 32 biomarkers, 19 and 15 were significantly elevated 2 h after LPS and UPEC exposure, respectively. IBTX significantly abrogated the elevations of 15 out of 19 biomarkers after LPS inoculation and 12 out of 15 biomarkers after UPEC inoculation. In a separate experiment, qPCR for IL-6, interferon-γ-induced protein 10 (CXCL10), and macrophage inflammatory protein 2 (CXCL2) in urothelium paralleled the changes measured in urine of these same biomarkers, supporting that urinary changes in biomarker levels reflected urothelial expression changes. These in vivo data demonstrated that BK channel activity is crucial in the urothelial host innate immune response, as measured by changes in urinary biomarkers, in UTI pathogenesis.

Knowledge of Pelvic Floor Disorders in Obstetrics.

OBJECTIVES: The aim of this study was to investigate knowledge and demographic factors associated with a lack of knowledge proficiency about urinary incontinence (UI) and pelvic organ prolapse (POP) among pregnant and postpartum women. METHODS: This was a cross-sectional survey of women receiving antepartum and postpartum care at 9 Connecticut sites. Knowledge was assessed using the validated Prolapse and Incontinence Knowledge Questionnaire. Lack of knowledge proficiency was defined as less than 80% and less than 50% correct responses on the Prolapse and Incontinence Knowledge Questionnaire UI and POP subscales. Logistic regression was used to evaluate unadjusted and adjusted odds ratios (ORs) and 95% confidence intervals (CIs). P < 0.05 was considered statistically significant. RESULTS: Surveys from 399 diverse pregnant and postpartum women were analyzed. Three quarters showed a lack of knowledge proficiency about UI and POP (74.2%, 70.6%). After adjustment, increased odds of lacking UI knowledge proficiency were associated with primiparity versus nulliparity (OR, 4.73; 95% CI, 2.24-9.98), Hispanic versus white race (OR, 2.72; 95% CI, 1.18-6.01), and having a high school diploma/General Education Development/less (OR, 3.17; 95% CI, 1.34-7.48) or some college (OR, 2.55; 95% CI, 1.08-6.01) versus bachelor's degree; greater lack of POP knowledge proficiency was associated with having a high school diploma/General Education Development versus bachelor's degree (OR, 2.11; 95% CI, 1.05-4.26) and never seeing a urologist/urogynecologist versus those who had (OR, 0.30; 95% CI, 0.12-0.77). Women working in a medical field versus those who did not demonstrated decreased odds of lacking UI and POP knowledge proficiency (ORs, 0.26 [95% CI, 0.13-0.52] and 0.38 [95% CI, 0.21-0.70]). CONCLUSIONS: Pregnant and postpartum women lack knowledge about UI and POP. Preconceptional counseling provides an opportunity for educational intervention.

Mouse urothelial genes associated with voiding behavior changes after ovariectomy and bladder lipopolysaccharide exposure.

AIMS: Symptoms from overactive bladder (OAB) and cystitis secondary to urinary tract infection (UTI) can be similar in post-menopausal women. Effects of ovariectomy (OVX) on voiding behavior after lipopolysaccharide (LPS) intravesical exposure (surrogate for cystitis) in mice were measured. Urothelial genes associated with micturition changes were identified. METHODS: Female C57BL6/J mice underwent OVX or sham surgeries (n = 10 for each). Voiding spot assays (VSA) were performed prior to surgery, 4 weeks post-surgery, and each time after 3 consecutive days of transurethral instillation of LPS. In another experiment, mice underwent either sham (n = 9) or OVX (n = 9) surgeries. Urothelial RNAs were collected 4 weeks post-surgery, day 1 and day 3 after LPS instillation. Mouse Gene 2.0 ST Arrays (entire 34 K transcripts) were used for microarray hybridization. A set of criteria was utilized to identify gene expression changes that mimicked voiding behavior changes. RESULTS: Three days after LPS exposure, OVX mice persisted with overactive whereas sham mice normalized voiding behavior. Nine urothelial paralleling voiding behavior changes were identified: IL6 (interleukin 6), IL6rα (Interleukin 6 receptor α), Ptgs2 (Prostaglandin-endoperoxide synthase 2 or COX-2), Ereg (epiregulin), Dusp6 (dual specificity phosphatase 6), Zfp948 (zinc finger protein 948), Zfp52 (Zinc finger protein 52), Gch1 (GTP cyclohydrolase 1), and Amd (S-adenosylmethionine decarboxylase). Three other genes, coding unknown proteins, were also identified: GM12840, GM23134, and GM26809. CONCLUSIONS: OVX mice persisted with increased voiding frequency after LPS. Urothelial genes that could mediate this voiding behavior include IL6, COX-2, and S-adenosylmethionine decarboxylase.

Urine Protein/Creatinine Ratios during Labor: A Prospective Observational Study.

PURPOSE: To evaluate the utility of urine protein/creatinine ratio (uPCR) measurements among healthy parturients at term we performed a prospective cohort study at a community teaching hospital. METHODS: Serial urine samples were collected. Ninety-three women contributed 284 urine samples. uPCRs were determined. Multiple imputation and paired sampled analysis was performed when appropriate. RESULTS: Two-thirds (63/93) of women had at least one measured uPCR ≥ 0.3. One-third (31/93) had a uPCR ≥ 0.3 at admission, including 39.1% (9/23) of women not in labor. Median (IQR) uPCRs increased during labor and after delivery: latent phase/no labor, 0.15 (0.06-0.32); active phase, 0.29 (0.10-0.58); early postpartum, 0.45 (0.18-1.36) (all p < 0.04). Median uPCRs were significantly < 0.3 in the latent phase and significantly > 0.3 in the immediate postpartum period (p < 0.01). Women who labored before cesarean delivery had the highest early postpartum uPCRs: median (IQR) 1.16 (0.39-1.80). A negative urine dipstick protein result did not exclude uPCR ≥ 0.3. uPCRs were similar when compared by method of urine collection. CONCLUSION: uPCR ≥ 0.3 is common among healthy women with uncomplicated pregnancies at term. uPCR increases during labor and is not a reliable measure of pathologic proteinuria at term or during the peripartum period.

Wnt Signaling and Survival of Women With High-Grade Serous Ovarian Cancer: A Brief Report.

OBJECTIVE: Ovarian cancer is the gynecologic malignancy with the highest case-fatality rate due to the development of chemotherapy resistance. Predictors of chemotherapy response are needed to guide chemotherapy selection and improve survival for patients with ovarian cancer. Wnt signaling may impact chemoresistance in ovarian cancer. METHODS: We studied The Cancer Genome Atlas patients with ovarian cancer treated with intraperitoneal or intravenous-only adjuvant chemotherapy. Cox regression tested associations of expression of 26 Wnt pathway genes with progression-free survival and overall survival. Permutation tests compared survival between chemotherapy groups stratified by expression. P values are two-tailed. RESULTS: Increased FZD3 was associated with increased survival (intraperitoneal group, overall survival: hazard ratio [HR], 0.25; 95% confidence interval [CI], 0.11-0.72, P = 0.009; progression-free survival: HR, 0.58; 95% CI, 0.37-0.92, P = 0.020) (intravenous-only group, overall survival: HR, 0.85; 95% CI, 0.72-0.99, P = 0.039; progression-free survival: HR, 0.83; 95% CI, 0.73-0.95, P = 0.006). Low FZD3 predicted decreased overall survival after intraperitoneal versus intravenous-only chemotherapy (21.7 vs 33.3 months, P < 0.0001). Increased APC2 was associated with decreased overall survival (HR, 1.22; 95% CI, 1.05-1.42; P = 0.009) and progression-free survival (HR, 1.28; 95% CI, 1.12-1.45; P = 0.0002). CONCLUSIONS: Up-regulated tumor Wnt signaling predicts increased ovarian cancer survival. FZD3 may predict benefit from intraperitoneal chemotherapy.

Electrical Stimulation Followed by Mesenchymal Stem Cells Improves Anal Sphincter Anatomy and Function in a Rat Model at a Time Remote From Injury.

BACKGROUND: We have explored cell-based therapy to aid anal sphincter repair, but a conditioning injury is required to direct stem cells to the site of injury because symptoms usually manifest at a time remote from injury. OBJECTIVE: We aimed to investigate the effect of local electrical stimulation followed by mesenchymal stem cell delivery on anal sphincter regeneration at a time remote from injury. DESIGN AND MAIN OUTCOME MEASURES: With the use of a rat model, electrical stimulation parameters and cell delivery route were selected based on in vivo cytokine expression and luciferase-labeled cell imaging of the anal sphincter complex. Three weeks after a partial anal sphincter excision, rats were randomly allocated to 4 groups based on different local interventions: no treatment, daily electrical stimulation for 3 days, daily stimulation for 3 days followed by stem cell injection on the third day, and daily electrical stimulation followed by stem cell injection on the first and third days. Histology-assessed anatomy and anal manometry evaluated physiology 4 weeks after intervention. RESULTS: The electrical stimulation parameters that significantly upregulated gene expression of homing cytokines also achieved mesenchymal stem cell retention when injected directly in the anal sphincter complex in comparison with intravascular and intraperitoneal injections. Four weeks after intervention, there was significantly more new muscle in the area of injury and significantly improved anal resting pressure in the group that received daily electrical stimulation for 3 days followed by a single injection of 1 million stem cells on the third day at the site of injury. LIMITATION: This was a pilot study and therefore was not powered for functional outcome. CONCLUSIONS: In this rat injury model with optimized parameters, electrical stimulation with a single local mesenchymal stem cell injection administered 3 weeks after injury significantly improved both new muscle formation in the area of injury and anal sphincter pressures.

Discovery of candidate tumor biomarkers for treatment with intraperitoneal chemotherapy for ovarian cancer.

Tumor mRNA expression was used to discover genes associated with worse survival or no survival benefit after intraperitoneal (IP) chemotherapy. Data for high grade serous ovarian cancer patients treated with IP (n = 90) or IV-only (n = 398) chemotherapy was obtained from The Cancer Genome Atlas. Progression free survival (PFS) and overall survival (OS) were compared between IP and IV groups using Kaplan-Meier analysis and Cox regression. Validations were performed by analyses of microarray and RNA-Seq mRNA expression data. PFS and OS were compared between IP and IV groups by permutation testing stratified by gene expression. P-values are two-tailed. IP chemotherapy increased PFS (26.7 vs 16.0 months, HR 0.43 (0.28-0.66), p = 0.0001) and OS (49.6 vs 38.2 months, HR 0.46 (0.25-0.83), p = 0.01). Increased expression of NCAM2 and TSHR and decreased expression of GCNT1 was associated with decreased PFS and OS after IV chemotherapy (p < 0.05). High tumor expression of LMAN2, FZD4, FZD5, or STT3A was associated with no significant PFS increase after IP compared to IV chemotherapy. Low expression of APC2 and high expression of FUT9 was associated with 5.5 and 7.2 months, respectively, decreased OS after IP compared to IV chemotherapy (p ≤ 0.007).

Survival of patients with structurally-grouped TP53 mutations in ovarian and breast cancers.

The objective of this study was to determine if ovarian cancer patients with a TP53 mutation grouped by location of the mutation within the p53 protein structure exhibit differential survival outcomes. Data from patients with high grade serous ovarian cancer (HGS OvCa) (N = 316) or breast cancer (BrCa) (N = 981) sequenced by The Cancer Genome Atlas (TCGA) was studied by Kaplan-Meier and Cox proportional hazards survival analysis. A TP53 DNA binding domain (BD) missense mutation (MM) occurred in 58.5% (185/316) of HGS OvCas and 16.8% (165/981) of BrCas. Patients with a TP53 DNA BD MM grouped by structural location had significantly different overall survival (OS) and progression free survival (PFS). Median OS (months) of HGS OvCa patients by structural group were: Sheet-loop-helix stabilizers, 31.1; DNA minor groove residue R248, 33.6; Wild-type, 34.2; all other MMs, 44.5; DNA major groove residues, 84.1, and zinc ion coordinating residues, 87.0 (log-rank p = 0.006). PFS of DNA major groove MM cases was longer than TP53 wild-type cases (19.1 versus 10.1 months, log-rank p = 0.038). HGS OvCa and BrCa patients with structurally-grouped TP53 DNA BD MMs have different survival outcomes.

Nonsurgical management of heterotopic abdominal pregnancy.

BACKGROUND: Heterotopic abdominal pregnancies with coexisting intrauterine pregnancies pose unique therapeutic challenges, and management options, particularly nonsurgical approaches, are limited. CASE: We present a case in which selective reduction of a heterotopic abdominal pregnancy during the second trimester using fetal intracardiac injection with potassium chloride enabled subsequent vaginal delivery of the intrauterine pregnancy at term. In addition, we summarize nine cases of nonsurgical management of heterotopic abdominal pregnancies, four of which involve potassium chloride selective reduction. Our case is unique in that the abdominal fetus remained as a stable lithopedion, allowing the uncomplicated conception and vaginal delivery of a second intrauterine pregnancy without need for surgical intervention. CONCLUSION: Our case report and literature review demonstrate the use of selective potassium chloride reduction in managing heterotopic abdominal pregnancy nonsurgically.

The predictive value of a cystocele for concomitant vaginal apical prolapse.

PURPOSE: Recent studies showing a correlation between descent of the anterior and apical vaginal compartments suggest that cystoceles may recur if associated apical prolapse is not corrected. However, to date the anatomical relationship of apical prolapse with respect to cystocele has been incompletely reported. We present the predictive value of a cystocele for clinically significant vaginal apical prolapse. MATERIALS AND METHODS: We retrospectively reviewed the records of all new patient visits to a urogynecology clinic in a 30-month period. Women with a point Ba value of -1 or greater (stage 2 cystocele and above) were included in analysis. Predictive values of clinically significant apical prolapse, defined as point C -3 or greater, were calculated and stratified by cystocele stage. RESULTS: A total of 385 women were included in study. Point Ba was the leading edge of prolapse in 83.9% of cases. The position of Ba strongly correlated with that of the vaginal apex (Spearman ρ = 0.769, p <0.001). Overall 59.7% of patients had a point C of -3 or greater. The finding of clinically significant apical prolapse increased significantly with increasing Ba values. Of patients with stage 2, 3 and 4 cystocele point C was -3 or greater in 42%, 85% and 100%, respectively. CONCLUSIONS: The finding of stage 2 or greater cystocele is highly suggestive of clinically significant apical vaginal descent to -3 or greater. Furthermore, as cystocele stage increases, the predictive value of apical prolapse also increases. Surgeons contemplating cystocele repair should have high suspicion for vaginal apical prolapse and consider concomitant repair.

Alterations in connective tissue metabolism in stress incontinence and prolapse.

PURPOSE: We describe current knowledge about collagen/elastin and extracellular matrix metabolism in the genitourinary tract with special emphasis on stress urinary incontinence. We also explored the influence of genetics and reproductive hormones on extracellular matrix metabolism. MATERIALS AND METHODS: We performed a MEDLINE® search from 1995 to February 2011 using the key words stress urinary incontinence, pelvic organ prolapse, extracellular matrix, collagen, elastin, matrix metalloproteinase, collagenase, tissue inhibitors of matrix metalloproteinase, elastin metabolism, elastase, connective tissue, supportive tissue, mechanical stress, biomechanical properties, selective estrogen receptor modulators, transforming growth factor-ß and wound healing. RESULTS: The literature searched produced data on 4 areas of significance for extracellular matrix metabolism in patients with stress urinary incontinence and prolapse, including collagen, elastin and transforming growth factor-ß. Data on collagen metabolism continue to support the hypothesis of increased turnover involving matrix metalloproteinases and serine proteases in pelvic tissues of affected individuals. Elastin metabolism studies suggest increased degradation but also abnormal elastin fiber synthesis. Epidemiological data indicate a genetic predisposition to abnormal extracellular matrix in affected individuals while human tissue and animal models reveal differential expression of candidate genes involved in structural proteins. Transforming growth factor-ß pathways have been documented to be involved in stress urinary incontinence in human tissues and animal models. Finally, these extracellular matrix metabolisms are modulated by reproductive hormones and selective estrogen receptor modulators. CONCLUSIONS: Pelvic tissue from women with stress urinary incontinence and pelvic organ prolapse show a genetic predisposition to abnormal extracellular matrix remodeling, which is modulated by reproductive hormones, trauma, mechanical stress load and aging. This progressive remodeling contributes to stress urinary incontinence/pelvic organ prolapse by altering normal tissue architecture and mechanical properties.

Reusable, reversibly sealable parylene membranes for cell and protein patterning.

The patterned deposition of cells and biomolecules on surfaces is a potentially useful tool for in vitro diagnostics, high-throughput screening, and tissue engineering. Here, we describe an inexpensive and potentially widely applicable micropatterning technique that uses reversible sealing of microfabricated parylene-C stencils on surfaces to enable surface patterning. Using these stencils it is possible to generate micropatterns and copatterns of proteins and cells, including NIH-3T3 fibroblasts, hepatocytes and embryonic stem cells. After patterning, the stencils can be removed from the surface, plasma treated to remove adsorbed proteins, and reused. A variety of hydrophobic surfaces including PDMS, polystyrene and acrylated glass were patterned using this approach. Furthermore, we demonstrated the reusability and mechanical integrity of the parylene membrane for at least 10 consecutive patterning processes. These parylene-C stencils are potentially scalable commercially and easily accessible for many biological and biomedical applications.

Controlling size, shape and homogeneity of embryoid bodies using poly(ethylene glycol) microwells.

Directed differentiation of embryonic stem (ES) cells is useful for creating models of human disease and could potentially generate a wide array of functional cell types for therapeutic applications. Methods to differentiate ES cells often involve the formation of cell aggregates called embryoid bodies (EBs), which recapitulate early stages of embryonic development. EBs are typically made from suspension cultures, resulting in heterogeneous structures with a wide range of sizes and shapes, which may influence differentiation. Here, we use microfabricated cell-repellant poly(ethylene glycol) (PEG) wells as templates to initiate the formation of homogenous EBs. ES cell aggregates were formed with controlled sizes and shapes defined by the geometry of the microwells. EBs generated in this manner remained viable and maintained their size and shape within the microwells relative to their suspension counterparts. Intact EBs could be easily retrieved from the microwells with high viability (>95%). These results suggest that the microwell technique could be a useful approach for in vitro studies involving ES cells and, more specifically, for initiating the differentiation of EBs of greater uniformity based on controlled microenvironments.

Microfluidic patterning for fabrication of contractile cardiac organoids.

The development of in vitro methods of engineering three-dimensional cardiac tissues can be useful for tissue replacement, diagnostics and drug discovery. Here, we introduce the use of patterned hyaluronic acid (HA) substrates generated using microfluidic patterning as a method of fabricating 3D cardiac organoids. HA micropatterns served as inductive templates for organoid assembly. Upon seeding, cardiomyocytes elongated and aligned along the pattern direction attaching preferentially to the glass substrate and the interface between HA patterns and glass substrate. After 3 days in culture, the linearly aligned myocytes detached from the surface and formed contractile cardiac organoids. The procedure can be utilized to simply, rapidly and inexpensively create in vitro cardiac tissue models.

Interplay of biomaterials and micro-scale technologies for advancing biomedical applications.

Micro-scale technologies have already dramatically changed our society through their use in the microelectronics and telecommunications industries. Today these engineering tools are also useful for many biological applications ranging from drug delivery to DNA sequencing, since they can be used to fabricate small features at a low cost and in a reproducible manner. The discovery and development of new biomaterials aid in the advancement of these micro-scale technologies, which in turn contribute to the engineering and generation of new, custom-designed biomaterials with desired properties. This review aims to present an overview of the merger of micro-scale technologies and biomaterials in two-dimensional (2D) surface patterning, device fabrication and three-dimensional (3D) tissue-engineering applications.

Co-culture of human embryonic stem cells with murine embryonic fibroblasts on microwell-patterned substrates.

Human embryonic stem (hES) cells are generally cultured as cell clusters on top of a feeder layer formed by mitotically inactivated murine embryonic fibroblasts (MEFs) to maintain their undifferentiated state. This co-culture system, which is typically used to expand the population of undifferentiated hES cells, presents several challenges since it is difficult to control cell cluster size. Large cell clusters tend to differentiate at the borders, and clusters with different sizes may lead to heterogeneous differentiation patterns within embryoid bodies. In this work, we develop a new approach to culture hES cells with controlled cluster size and number through merging microfabrication, and biomaterials technologies. Polymeric microwells were fabricated and used to control the size and uniformity of hES cell clusters in co-culture with MEFs. The results show that it is possible to culture hES cells homogeneously while keeping their undifferentiated state as confirmed by the expression of stem cell markers octamer binding protein 4 (Oct-4) and alkaline phosphatase (ALP). In addition, these clusters can be recovered from the microwells to generate nearly homogeneous cell aggregates for differentiation experiments.

Micromolding of photocrosslinkable chitosan hydrogel for spheroid microarray and co-cultures.

Bioengineering approaches, such as co-cultures of multiple cell types, that aim to mimic the physiological microenvironment may be beneficial for optimizing cell function and for engineering tissues in vitro. This study describes a novel method for preparing a spheroid microarray on microfabricated hydrogels, alone or in co-cultures. Photocrosslinkable chitosan was synthesized and utilized for fabricating hydrogel microstructures through a micromolding process. The chitosan surface was initially cell repellent but became increasingly cell adhesive over time. By using this unique property of chitosan hydrogels, it was possible to generate patterned co-cultures of spheroids and support cells. In this scheme, cells were initially microarrayed within low shear stress regions of microwells. Human hepatoblastoma cells, Hep G2, seeded in these wells formed spheroids with controlled sizes and shapes and stably secreted albumin during the culture period. The change of cell adhesive properties in the chitosan surface facilitated the adhesion and growth of a second cell type, NIH-3T3 fibroblast, and therefore enabled co-cultures of hepatocyte spheroids and fibroblast monolayers. This co-culture system could be a useful platform for studying heterotypic cell-cell interactions, for drug screening, and for developing implantable bioartificial organs.

Micromolding of shape-controlled, harvestable cell-laden hydrogels.

Encapsulation of mammalian cells within hydrogels has great utility for a variety of applications ranging from tissue engineering to cell-based assays. In this work, we present a technique to encapsulate live cells in three-dimensional (3D) microscale hydrogels (microgels) of controlled shapes and sizes in the form of harvestable free standing units. Cells were suspended in methacrylated hyaluronic acid (MeHA) or poly(ethylene glycol) diacrylate (PEGDA) hydrogel precursor solution containing photoinitiator, micromolded using a hydrophilic poly(dimethylsiloxane) (PDMS) stamp, and crosslinked using ultraviolet (UV) radiation. By controlling the features on the PDMS stamp, the size and shape of the molded hydrogels were controlled. Cells within microgels were well distributed and remained viable. These shape-specific microgels could be easily retrieved, cultured and potentially assembled to generate structures with controlled spatial distribution of multiple cell types. Further development of this technique may lead to applications in 3D co-cultures for tissue/organ regeneration and cell-based assays in which it is important to mimic the architectural intricacies of physiological cell-cell interactions.

Micromolding of photocrosslinkable hyaluronic acid for cell encapsulation and entrapment.

Micropatterning of hydrogels is potentially useful for a variety of applications, including tissue engineering, fundamental biological studies, diagnostics, and high-throughput screening. Although synthetic polymers have been developed for these applications, natural polymers such as polysaccharides may have advantages for biological samples and cell-based devices because they are natural components of the in vivo microenvironment. In this study, we synthesized and used hyaluronic acid (HA) modified with photoreactive methacrylates to fabricate microstructures as functional components of microfabricated devices. To demonstrate the universality of this approach, two types of microstructures were formed. In the first approach, HA microstructures were fabricated and used as docking templates to enable the subsequent formation of cell microarrays within low shear stress regions of the patterns. Cells within these microwells remained viable, could generate spheroids, and could be retrieved using mechanical disruption. In the second approach, cells were encapsulated directly within the HA hydrogels. Arrays of viable embryonic stem (ES) cells or fibroblasts were encapsulated within HA hydrogels and could later be recovered using enzymatic digestion of the microstructures. These results demonstrate that it is possible to incorporate photocrosslinkable HA, a natural, versatile, degradable, and biocompatible biopolymer, into micro-electromechanical systems.