Development of a Flexible Sensor-Integrated Tissue Patch to Monitor Early Organ Rejection Processes Using Impedance Spectroscopy.

Heart failure represents a primary cause of hospitalization and mortality in both developed and developing countries, often necessitating heart transplantation as the only viable recovery path. Despite advances in transplantation medicine, organ rejection remains a significant post-operative challenge, traditionally monitored through invasive endomyocardial biopsies (EMB). This study introduces a rapid prototyping approach to organ rejection monitoring via a sensor-integrated flexible patch, employing electrical impedance spectroscopy (EIS) for the non-invasive, continuous assessment of resistive and capacitive changes indicative of tissue rejection processes. Utilizing titanium-dioxide-coated electrodes for contactless impedance sensing, this method aims to mitigate the limitations associated with EMB, including procedural risks and the psychological burden on patients. The biosensor's design features, including electrode passivation and three-dimensional microelectrode protrusions, facilitate effective monitoring of cardiac rejection by aligning with the heart's curvature and responding to muscle contractions. Evaluation of sensor performance utilized SPICE simulations, scanning electron microscopy, and cyclic voltammetry, alongside experimental validation using chicken heart tissue to simulate healthy and rejected states. The study highlights the potential of EIS in reducing the need for invasive biopsy procedures and offering a promising avenue for early detection and monitoring of organ rejection, with implications for patient care and healthcare resource utilization.

Using Rapid Prototyping to Develop a Cell-Based Platform with Electrical Impedance Sensor Membranes for In Vitro RPMI2650 Nasal Nanotoxicology Monitoring.

Due to advances in additive manufacturing and prototyping, affordable and rapid microfluidic sensor-integrated assays can be fabricated using additive manufacturing, xurography and electrode shadow masking to create versatile platform technologies aimed toward qualitative assessment of acute cytotoxic or cytolytic events using stand-alone biochip platforms in the context of environmental risk assessment. In the current study, we established a nasal mucosa biosensing platform using RPMI2650 mucosa cells inside a membrane-integrated impedance-sensing biochip using exclusively rapid prototyping technologies. In a final proof-of-concept, we applied this biosensing platform to create human cell models of nasal mucosa for monitoring the acute cytotoxic effect of zinc oxide reference nanoparticles. Our data generated with the biochip platform successfully monitored the acute toxicity and cytolytic activity of 6 mM zinc oxide nanoparticles, which was non-invasively monitored as a negative impedance slope on nasal epithelial models, demonstrating the feasibility of rapid prototyping technologies such as additive manufacturing and xurography for cell-based platform development.

Mastering of NIL Stamps with Undercut T-Shaped Features from Single Layer to Multilayer Stamps.

Biomimetic structures such as structural colors demand a fabrication technology of complex three-dimensional nanostructures on large areas. Nanoimprint lithography (NIL) is capable of large area replication of three-dimensional structures, but the master stamp fabrication is often a bottleneck. We have demonstrated different approaches allowing for the generation of sophisticated undercut T-shaped masters for NIL replication. With a layer-stack of phase transition material (PTM) on poly-Si, we have demonstrated the successful fabrication of a single layer undercut T-shaped structure. With a multilayer-stack of silicon oxide on silicon, we have shown the successful fabrication of a multilayer undercut T-shaped structures. For patterning optical lithography, electron beam lithography and nanoimprint lithography have been compared and have yielded structures from 10 µm down to 300 nm. The multilayer undercut T-shaped structures closely resemble the geometry of the surface of a Morpho butterfly, and may be used in future to replicate structural colors on artificial surfaces.

Monitoring tissue-level remodelling during inflammatory arthritis using a three-dimensional synovium-on-a-chip with non-invasive light scattering biosensing.

Rheumatoid arthritis is a chronic, systemic joint disease in which an autoimmune response translates into an inflammatory attack resulting in joint damage, disability and decreased quality of life. Despite recent introduction of therapeutic agents such as anti-TNFα, even the best current therapies fail to achieve disease remission in most arthritis patients. Therefore, research into the mechanisms governing the destructive inflammatory process in rheumatoid arthritis is of great importance and may reveal novel strategies for the therapeutic interventions. To gain deeper insight into its pathogensis, we have developed for the first time a three-dimensional synovium-on-a-chip system in order to monitor the onset and progression of inflammatory synovial tissue responses. In our study, patient-derived primary synovial organoids are cultivated on a single chip platform containing embedded organic-photodetector arrays for over a week in the absence and presence of tumor-necrosis-factor. Using a label-free and non-invasive optical light-scatter biosensing strategy inflammation-induced 3D tissue-level architectural changes were already detected after two days. We demonstrate that the integration of complex human synovial organ cultures in a lab-on-a-chip provides reproducible and reliable information on how systemic stress factors affect synovial tissue architectures.

Optimized plasma-assisted bi-layer photoresist fabrication protocol for high resolution microfabrication of thin-film metal electrodes on porous polymer membranes.

Structured metal thin-film electrodes are heavily used in electrochemical assays to detect a range of analytes including toxins, biomarkers, biological contaminants and cell cultures using amperometric, voltammetric and impedance-based (bio)sensing strategies as well as separation techniques such as dielectrophoresis. Over the last decade, thin-film electrodes have been fabricated onto various durable and flexible substrates including glass, silicon and polymers. However, the combination of thin-film technology with porous polymeric substrates frequently used for biochips often results in limited resolution and poor adhesion of the metal thin-film, thus severely restricting reproducible fabrication and reliable application in e.g. organ-on-a-chip systems. To overcome common problems associated with micro-structured electrode manufacturing on porous substrates, we have optimized a bi-layer lift-off method for the fabrication of thin-film electrodes on commercial porous polyester membranes using a combination of LOR3A with AZ5214E photoresists. To demonstrate practical application of our porous electrode membranes for trans-epithelial electrical resistance measurements a tetrapolar biosensing set-up was used to eliminate the artificial resistance of the porous polymer membrane from the electrochemical recordings. Furthermore, barrier resistance of Bewo trophoblast epithelial cells was compared to a standard Transwell assay readout using a EVOM2 volt-ohm meter. •Bi-layer photo resist lift-off yields resolution down to 2.5 µm.•Argon Plasma-assisted lift-off results in improved adhesion of gold thin films and eliminates the need for chromium adhesion layers.•Membrane electrodes can be used for elimination of the porous membrane resistance during tetra-polar epithelial resistance measurements.

Latest Trends in Biosensing for Microphysiological Organs-on-a-Chip and Body-on-a-Chip Systems.

Organs-on-chips are considered next generation in vitro tools capable of recreating in vivo like, physiological-relevant microenvironments needed to cultivate 3D tissue-engineered constructs (e.g., hydrogel-based organoids and spheroids) as well as tissue barriers. These microphysiological systems are ideally suited to (a) reduce animal testing by generating human organ models, (b) facilitate drug development and (c) perform personalized medicine by integrating patient-derived cells and patient-derived induced pluripotent stem cells (iPSCs) into microfluidic devices. An important aspect of any diagnostic device and cell analysis platform, however, is the integration and application of a variety of sensing strategies to provide reliable, high-content information on the health status of the in vitro model of choice. To overcome the analytical limitations of organs-on-a-chip systems a variety of biosensors have been integrated to provide continuous data on organ-specific reactions and dynamic tissue responses. Here, we review the latest trends in biosensors fit for monitoring human physiology in organs-on-a-chip systems including optical and electrochemical biosensors.

Anatomical Evidence of Acupuncture Meridians in the Human Extracellular Matrix: Results from a Macroscopic and Microscopic Interdisciplinary Multicentre Study on Human Corpses.

For more than 2500 years, acupuncture has been applied to support the healing of different diseases and physiologic malfunctions. Although various theories of the meridian system and mechanisms were formulated to explain the functional basis of acupuncture, the anatomical basis for the concept of meridians has not been resolved. The aim of the present study was to search for replicable anatomical structures that could relate to meridians. To this end, four human specimens and additionally two lower legs were dissected anatomically. Our study found evidence that acupuncture meridians were part of the human extracellular matrix and that fascia was an important part of the anatomic substrate of acupuncture meridians. At the same time, we found vessel-nerve-bundles, which were hypothesized to account for 80% of acupuncture points, only in a few acupuncture points. Therefore, our findings contradict the theory that acupuncture points are only located along the nervous channels.

Engineering of three-dimensional pre-vascular networks within fibrin hydrogel constructs by microfluidic control over reciprocal cell signaling.

Reengineering functional vascular networks in vitro remains an integral part in tissue engineering, since the incorporation of non-perfused tissues results in restricted nutrient supply and limited waste removal. Microfluidic devices are routinely used to mimic both physiological and pathological vascular microenvironments. Current procedures either involve the investigation of growth factor gradients and interstitial flow on endothelial cell sprouting alone or on the heterotypic cell-cell interactions between endothelial and mural cells. However, limited research has been conducted on the influence of flow on co-cultures of these cells. Here, we exploited the ability of microfluidics to create and monitor spatiotemporal gradients to investigate the influence of growth factor supply and elution on vascularization using static as well as indirect and direct flow setups. Co-cultures of human adipose-derived stem/stromal cells and human umbilical vein endothelial cells embedded in fibrin hydrogels were found to be severely affected by diffusion limited growth factor gradients as well as by elution of reciprocal signaling molecules during both static and flow conditions. Static cultures formed pre-vascular networks up to a depth of 4 mm into the construct with subsequent decline due to diffusion limitation. In contrast, indirect flow conditions enhanced endothelial cell sprouting but failed to form vascular networks. Additionally, complete inhibition of pre-vascular network formation was observable for direct application of flow through the hydrogel with decline of endothelial cell viability after seven days. Using finite volume CFD simulations of different sized molecules vital for pre-vascular network formation into and out of the hydrogel constructs, we found that interstitial flow enhances growth factor supply to the cells in the bulk of the chamber but elutes cellular secretome, resulting in truncated, premature vascularization.

Perioperative high-dose rate brachytherapy using a bendy applicator (flab): treatment results of 74 patients.

BACKGROUND: Radiotherapy plays a pivotal role in tumor treatment. Brachytherapy as an additional radiation technique allows local dose increments in areas at high risk of local failure. PATIENTS AND METHODS: Our past 15-year experience with tissue-equivalent bendy applicator brachytherapy at the University Hospital Münster, Germany was reviewed. A series of 74 consecutive patients who had mainly been treated for sarcomas with perioperative brachytherapy was analyzed with a focus on local relapse-free survival and side-effects. RESULTS: The 5-year local control rate was 73% in primary treatment situations with a significant influence of additional external irradiation, surgical margin depth and tumor entity. Late sequelae of combined modality treatment were observed in 40 patients (54%) and mainly concerned wound healing (n = 18, 24%). CONCLUSION: A high-risk collective, in view of local failure, showed adequate local control rates as well as acceptable late sequelae. Flab brachytherapy is a good treatment option to achieve local radiation dose increments in patients at high risk of local failure.

Organ movements and dose exposures in teletherapy of prostate cancer using a rectal balloon.

BACKGROUND AND PURPOSE: During radiotherapy of localized prostate cancer, organ movements for the dose exposure of organs at risk like rectum, urinary bladder and urethra play, inter alia, a significant role. One possibility of internal organ stabilizing is offered by the usage of a rectal balloon during radiotherapy. The influence on organ movements and dose allocation of the organs at risk is unknown. PATIENTS AND METHODS: Twelve patients (Table 1) were characterized based on planning-CT's regarding organ movements and organ doses using a rectal balloon, inflated with 0 ml and 60 ml air. For the determination of the organ doses, three-dimensional conformal radiation plans (3-field-pelvis box) with a cumulative dose of 59.4 Gy were created, and the dose-volume-histograms for the anterior rectal wall, the posterior rectal wall, the rectal mucosa, the whole rectum, as well as the urinary bladder were compared (Figures 1 and 2). RESULTS: The application of a 60 ml air-filled rectal balloon during each fraction of teletherapy led to significant organ movements of the anterior and posterior rectal wall and to a reduction of the transversal prostate diameter, as well as to a changed organ dose exposure of the organs at risk. A ventral shift of the anterior rectal wall (maximum 0.8 cm, mean 0.4 cm) was shown, as well as a dorsal shift of the posterior rectal wall (maximum 1.2 cm, mean 0.7 cm), associated with a transversal prostate diameter decrease (maximum 0.8 cm, mean 0.3 cm) (Table 2, Figure 3). The organ dose of the anterior rectal wall increased significantly (maximum 1.3 Gy, mean 0.5 Gy) during application of a rectal balloon, the one of the posterior rectal wall decreased significantly (maximum 18.6 Gy, mean 6.5 Gy). Related to the entire rectal mucosa and the rectum as a complete organ, a decrease of the maximum doses was shown (rectal mucosa: maximum 9.1 Gy, mean 3.0 Gy; rectum: maximum 9.4 Gy, mean 3.7 Gy). The organ dose of the urinary bladder did not show significant changes (Tables 3 and 4, Figures 4 to 7). CONCLUSION: The application of a rectal balloon in teletherapy of localized prostate cancer leads to significantly changed dose exposition of organs at risk. The decreased dose exposure of the posterior rectal wall and the rectal mucosa is opposed by the higher organ dose of the anterior rectal wall. It has to be shown weather documented organ dose exposure is associated with short and long-term consequences.

Results and follow-up of locally advanced cancer of the exocrine pancreas treated with radiochemotherapy.

UNLABELLED: In locally advanced carcinoma of the exocrine pancreas combined radiochemotherapy has been established as a standard treatment. MATERIALS AND METHODS: Two different treatment schemes have been consecutively used. Between 1/1994 and 12/2001, a total of 110 patients with locally advanced adenocarcinoma of the pancreas were treated with hyperfractionated accelerated radiotherapy to a total dose of 44.8 Gy combined with 5-fluorouracil (5-FU) (600 mg/m2) and folinic acid (FA) (300 mg/m2) injection. Chemotherapy was repeated monthly in non-progressive disease. From 1/2002 to 11/2003, in another 15 consecutive patients, chemotherapy was changed to gemcitabine (Gem) (300 mg/m2) and cisplatinum (Cis) (30 mg/m2), followed by gemcitabine (1000 mg/m2) every 2 weeks in non-progressive patients. RESULTS: Median survival in the 5-FU/FA group was 10.3 months with a 1-year survival of 46.6% and a 2-year survival of 20.1%. Median time to progression was 8.6 months. Treatment was well tolerated with nausea/vomiting grade I/II in 58.2%, grade III/IV in 14.5%, diarrhea grade I/II in 27.3%, leucopenia/thrombopenia grade I/II in 21.8%, grade III/IV in 7.2%, and mucositis grade III/IV in 7.2%. In the Gem/Cis group, median survival was 13.8 months with a 1-year survival of 54.9% and a 2-year survival of 24.4%. The toxicity data also revealed comparable feasibility: nausea/vomiting grade I/II in 46.7%, grade III/IV in 20%, diarrhea grade I/II in 20%, leucopenia/thrombopenia grade I/II in 26. 7%, and grade III/IV in 13.3%. CONCLUSION: Radiochemotherapy in locally advanced pancreatic cancer is an effective and well-tolerated treatment. The long-term efficacy concerning survival is limited. The integration of predictive factors and new chemotherapeutic agents like gemcitabine in the multimodality treatment may give a more promising perspective. Because of the narrow therapeutic index of gemcitabine-based radiochemotherapy schemes, a feasible combination of radiotherapy treatment volume and gemcitabine dose must be found.

PSA course after definitive high-dose radiotherapy of localized prostate cancer.

AIM: After radical prostatectomy, PSA levels that reach near zero values in less than 14 days are associated with a favourable prognosis. The aim of this analysis was to investigate whether PSA also declines to near zero values after combined tele-brachytherapy. MATERIALS AND METHODS: Forty-one patient, treated with combined tele-brachytherapy for prostate cancer, were followed for at least 2 years after treatment with repeated PSA measurements. RESULTS: PSA values <1.0 ng/ml were only reached after 15 months; near zero PSA levels were not reached until 18-24 months after treatment (median: 0.25 ng/ml). CONCLUSION: A PSA decline to near zero values occurs after definitive tele-brachytherapy, but it takes longer than after surgery (18-24 months).

The effect of sequential radiochemotherapy in preirradiated malignant gliomas in a phase II study.

The optimum treatment strategy for recurrent high-grade gliomas in preirradiated areas remains undefined. This prospective non-randomized phase II study was undertaken to evaluate a radiochemotherapy protocol against this disease. Fourteen patients (median age 61 years) were treated according to a standardized treatment protocol consisting of sequential radiochemotherapy. The chemotherapy (temozolomide) was carried out over a duration of five sequential days (Mon.-Fri.) with a dose of 200 mg/m2/d. Chemotherapy courses were repeated in 4-week intervals (days 1, 29, 57, etc.) until clinical progression. Radiotherapy with 30 Gy over 3 weeks (5 x 2 Gy/week) was interposed between the first two chemotherapy courses (days 8-26). Eleven/fourteen patients had no acute side effects. One patient suffered from acute thrombocytopenia/leucocytopenia, one patient developed mental degradation (treatment stopped at 24 Gy) and another severe cephalgia. Until now, 10 out of 14 patients have died due to disease progression. Median survival (Kaplan-Meier method) amounts to 30 weeks with a 6-months progression-free survival of 30%. Four of fourteen patients are still alive 8, 10, 11 and 12 months after therapy. Late treatment toxicities have not been observed so far. The reported radiochemotherapy protocol seems to be feasible for these patients with only few treatment alternatives and does not lead to a remarkable increase in acute toxicity. Palliative and survival benefits are modest. Evaluation of late toxicities needs further investigations.

Hemoglobin as an independent prognostic factor in the radiotherapy of head and neck tumors.

PURPOSE: The purpose of this study was to analyze the prognostic value of baseline hemoglobin levels before radiotherapy in patients with head and neck tumors. PATIENTS AND METHODS: In a retrospective study with a median follow-up of 43 months, we analyzed the results of 214 patients irradiated for head and neck cancer between January 1, 1990 and January 1, 1998 (180 men and 34 women; median age 58 years). The treatment concept consisted in adjuvant radiotherapy in 58 patients, 77 patients received definitive radiochemotherapy, 42 patients definitive radiotherapy, and 37 patients reirradiation for in-field recurrence. Baseline hemoglobin values were divided in four groups of the same patient number (quartiles). Several known prognostic factors like sex, age, tumor stage, histologic grading, performance status, and treatment scheme were analyzed for their influence on overall and event-free survival and correlated with pretreatment hemoglobin values (Kaplan-Meier method). In addition, univariate und multivariate logistic regression analyses were carried out to evaluate the effect of baseline hemoglobin on response rates. RESULTS: The median survival (event-free survival) of all patients amounted to 15 months (10 months). 25%, 50%, and 75% of patients had hemoglobin values < 11.2 g/dl, < 12.7 g/dl, and < 13.9 g/dl, respectively. In the univariate analysis, the following variables were significant prognostic factors for overall/event-free survival (log-rank test): treatment concept (p < 0.001/p < 0.001), tumor stage (p < 0.001/p < 0.001), general condition (p < 0.001/p < 0.001), and pretreatment hemoglobin (p = 0.014/p = 0.05). Multivariate analysis (Cox) proved these parameters to be independent of each other. In addition, response rate after radiation showed a strong association between hemoglobin and local control probability (p = 0.02). CONCLUSION: In this retrospective analysis, baseline hemoglobin level was shown to be an independent significant prognostic factor in radiotherapy of head and neck cancer patients. Therefore, the value of tumor anemia as a prognostic factor should be emphasized more.

Simulator verification of the accuracy of patient repositioning after virtual simulation. Is physical simulation still needed?

PURPOSE: To evaluate the frequency and amount of displacements after repositioning a patient on the physical simulator following virtual simulation. MATERIAL AND METHODS: After laser marking at the CT scanner and virtual simulation, patients were repositioned on the simulator. The isocenter obtained from the calculated table movements was checked by fluoroscopically measuring the distances to standardized anatomic landmarks and comparing them to the treatment plan. RESULTS: In 86% of patients, displacements were < or = 0.5 cm. There was no significant difference between the supine and prone position, diagnosis categories or CT reconstruction indices. The use of immobilization devices and cranial versus body stem localization did make a significant difference. Rates of exact repositioning were high in brain and head and neck patients and comparatively low in abdominal tumors and breast cancer. CONCLUSIONS: Immobilization devices play an important role for the precision of radiotherapy. Whenever precise positioning is possible (e. g. with a head mask), virtual simulation alone might be sufficient. Patients with abdominal and breast tumors, were repositioning precision is often suboptimal, might profit from an additional physical simulation.

Microscopic residual disease is a risk factor in the primary treatment of breast cancer.

OBJECTIVES: In the primary treatment of breast cancer, postoperative radiotherapy is performed in high-risk patients after mastectomy and in patients who received breast conserving surgery. In a retrospective analysis, our mono-institutional results of postoperative irradiation have been evaluated. PATIENTS AND METHODS: Between 1992 and 1996, 500 patients have been irradiated after surgery for primary breast cancer. Of these, 489 patients had no initial metastases. 89 patients with loco-regional disease had a mastectomy, 400 patients were irradiated after breast conserving surgery. Radiotherapy at the chest wall was performed with 50 Gy and 2 Gy fractions. After microscopically incomplete resection, an electron boost of 10 Gy was given. The ipsilateral lymph nodes were irradiated with 50 Gy when there was extensive lymph node involvement or invasion of tumor in the axillary fat tissue. RESULTS: The 5-year local control rate after mastectomy was 97.4% and 91.2% after breast conserving surgery. The only statistically significant risk factor for local failure was microscopically incomplete resection. The corresponding 5-year local control rates for microscopically incomplete and complete resections were 76.4% and 92.7% (p = 0.01). The risk of local relapse was increased with both marginal invasive and marginal DCIS-tissue. 86.6% of local relapses were in the same quadrant. CONCLUSIONS: High-risk patients after mastectomy and patients with breast conserving surgery achieve a high local control rate with postoperative irradiation. After microscopically incomplete resection, there is an increased risk for local relapse.