Pflegekompetenzgesetz – Gehen vor Enthusiasmus die Potenziale der Digitalisierung auf dem Weg verloren?

Am 19.12.2023 stellten das Bundesministerium für Gesundheit, der Deutsche Pflegerat und die Bundesärztekammer das Eckpunktepapier zum Pflegekompetenzgesetz vor. Der Gesetzentwurf soll bis zum Sommer 2024 ausgearbeitet werden. Im Kern geht es um die Angleichung des rechtlichen Entscheidungs- und Handlungsspielraums von Pflegefachpersonen an deren vorhandene pflegefachliche Kompetenz. Die Reaktionen auf das Eckpunktepapier waren überwiegend positiv. Zu wenig Beachtung finden allerdings die Anwendung und Erweiterung pflegerischer Fachkompetenz mit Blick auf die zunehmenden Möglichkeiten digitaler Unterstützung. On December 19, 2023, the Federal Ministry of Health, the German Nursing Council and the German Medical Association presented the key points paper on the Nursing Competence Act. The draft law is to be drawn up by summer 2024. At its core, it is about aligning the legal scope of decision-making and action of nursing professionals with their existing nursing expertise. Reactions to the key points paper have been largely positive. However, too little attention has been paid to the application and expansion of nursing expertise in view of the increasing possibilities of digital support.

Evidence of human milk oligosaccharides in maternal circulation already during pregnancy: a pilot study

Human milk oligosaccharides (HMOs) are bioactive glycans linked with health benefits to both the breast-fed infant and lactating mother. We hypothesized that HMOs are present before lactation, already during pregnancy, and are influenced by maternal body composition. In a pilot study, we investigated individual and temporal variations in HMO composition and concentration in maternal serum at gestational weeks 10-14 ( visit 1), 20-24 ( visit 2), and 30-35 (visit 3) (V1, V2, and V3, respectively) and associations with maternal body composition. HMOs were quantified by HPLC and confirmed by enzymatic digest and mass spectrometry. Associations of maternal prepregnancy body mass index (BMI), subcutaneous adipose tissue (SAT) thickness, and adipokines with absolute and relative HMO concentrations were analyzed by Spearman correlation. We identified 16 HMOs and 2 oligosaccharides not common to human milk. HMO concentration and composition varied with gestational age and secretor status. HMO concentration increased with gestational age and changed from a predominantly sialylated profile at V1 to a more balanced fucosylated-to-sialylated ratio at V3, mostly due to a profound increase in 2'-fucosyllactose (2'-FL), reflecting secretor phenotype. In secretor-positive women, BMI was negatively correlated with 2'-FL at V2. SAT at V1 and V2 were strongly negatively correlated with 2'-FL concentrations. This pilot study shows that prenatal HMOs are present in maternal serum, suggesting roles for HMOs already during pregnancy. Our result that maternal body composition is associated with prenatal HMOs might indicate that maternal metabolism modulates HMO composition with unknown implications for maternal and fetal health already during pregnancy.

A hormone-dependent feedback-loop controls androgen receptor levels by limiting MID1, a novel translation enhancer and promoter of oncogenic signaling

BACKGROUND

High androgen receptor (AR) level in primary tumour predicts increased prostate cancer (PCa)-specific mortality. Furthermore, activations of the AR, PI3K, mTOR, NFκB and Hedgehog (Hh) signaling pathways are involved in the fatal development of castration-resistant prostate cancer during androgen ablation therapy. MID1, a negative regulator of the tumor-suppressor PP2A, is known to promote PI3K, mTOR, NFκB and Hh signaling. Here we investigate the interaction of MID1 and AR.

METHODS

AR and MID1 mRNA and protein levels were measured by qPCR, Western blot and immunohistochemistry. Co-immunoprecipitation followed by PCR and RNA-pull-down followed by Western blot was used to investigate protein-mRNA interaction, chromatin-immunoprecipitation followed by next-generation sequencing for identification of AR chromatin binding sites. AR transcriptional activity and activity of promoter binding sites for AR were analyzed by reporter gene assays. For knockdown or overexpression of proteins of interest prostate cancer cells were transfected with siRNA or expression plasmids, respectively.

RESULTS

The microtubule-associated MID1 protein complex associates with AR mRNA via purine-rich trinucleotide repeats, expansions of which are known to correlate with ataxia and cancer. The level of MID1 directly correlates with the AR protein level in PCa cells. Overexpression of MID1 results in a several fold increase in AR protein and activity without major changes in mRNA-levels, whereas siRNA-triggered knockdown of MID1 mRNA reduces AR-protein levels significantly. Upregulation of AR protein by MID1 occurs via increased translation as no major changes in AR protein stability could be observed. AR on the other hand, regulates MID1 via several functional AR binding sites in the MID1 gene, and, in the presence of androgens, exerts a negative feedback loop on MID1 transcription. Thus, androgen withdrawal increases MID1 and concomitantly AR-protein levels. In line with this, MID1 is significantly over-expressed in PCa in a stage-dependent manner.

CONCLUSION

Promotion of AR, in addition to enhancement of the Akt-, NFκB-, and Hh-pathways by sustained MID1-upregulation during androgen deprivation therapy provides a powerful proliferative scenario for PCa progression into castration resistance. Thus MID1 represents a novel, multi-faceted player in PCa and a promising target to treat castration resistant prostate cancer.

Abstract P1-08-07: High tumor CD68 mRNA content (intratumoral macrophages) predicts response to neoadjuvant chemotherapy

Background

Immune cell infiltrates have been shown to play a prominent role with regard to prognosis of node negative breast cancer (Schmidt et al 2008). Moreover, it has been shown that B-cells and T-Cells are of particular importance for the response to chemotherapy (Schmidt et al. 2012). However, the role of macrophages remains unclear. It has been assumed, that tumor-associated macrophages play a role in promoting tumorigenesis. Still their role with regard to therapy prediction is unknown. Here we tested wether the infiltration of macrophages is associated with the response to neoadjuvant chemotherapy.

Materials and Methods

Pretreatment core cut biopsies from n = 100 patients with PBC treated within a randomized phase II trial (1) of anthracyline/taxane based NAC were examined. RNA from formalin-fixed, paraffin embedded (FFPE) routine biopsies were extracted using a bead-based extraction method (STRATIFYER XTRAKT kits). CD68 and ESR1, PGR, HER2, Ki67 as well as CALM2 as a house keeping gene were measured via a multiplex quantitative RT-PCR (RT-qPCR). Correlation analyses and partitioning tests were performed using the SAS JMP® 9.0.0 software.

Results

CD68 mRNA exhibited a normal data distribution (Median expression 40-DCT 34,66) in the core needle biopsies of advanced breast tumors. CD68 mRNA correlated strongly with Ki67 mRNA levels (Spearman r = 0,46; p<0,001), whereas there is virtually no correlation with other classical biomarkers such as ESR1, PGR and HER2. Partitioning analysis revealed that CD68 mRNA levels are superior to the previously and prospectively validated response markers ESR1 mRNA and HER2 mRNA. When using the median mRNA expression as an objective cut-off measurement no tumor having low CD68 mRNA expression did respond to chemotherapy, while 22% of the CD68 positive tumors responded by pathological complete response (ypT0ypN0). Based on molecular subtyping into Luminal, HER2 positive and Triple-Negative with predefined Cut-Off values for ESR1mRNA and HER2 mRNA levels, high CD68 were particularly informative within luminal tumors (22% pCR versus 0% pCR rate) and Triple negative tumors (38% pCR versus 0% pCR rate).

Conclusion

The presence of macrophages indicates tumors being sensitive to chemotherapy beyond the prospectively validated ESR1 and HER2 mRNA determinations (2), both in luminal and triple negative tumors. The mRNA expression levels of CD68 provide additional information beyond conventional subtyping and might therefore be useful for early assessment of non-response to chemotherapy und subsequent treatment planning.

1) Schneeweiss et al, Ann Oncol 2011

2) Denkert et al, Ann Oncol 2013.

Citation Information: Cancer Res 2013;73(24 Suppl): Abstract nr P1-08-07.

A common 56-kilobase deletion in a primate-specific segmental duplication creates a novel butyrophilin-like protein

Background

The Butyrophilin-like (BTNL) proteins are likely to play an important role in inflammation and immune response. Like the B7 protein family, many human and murine BTNL members have been shown to control T lymphocytes response, and polymorphisms in human BTNL2 have been linked to several inflammatory diseases, such as pulmonary sarcoidosis, inflammatory bowel disease and neonatal lupus.

Results

In this study we provide a comprehensive population, genomic and transcriptomic analysis of a 56-kb deletion copy number variant (CNV), located within two segmental duplications of two genes belonging to the BTNL family, namely BTNL8 and BTNL3. We confirm the presence of a novel BTNL8*3 fusion-protein product, and show an influence of the deletion variant on the expression level of several genes involved in immune function, including BTNL9, another member of the same family. Moreover, by genotyping HapMap and human diversity panel (HGDP) samples, we demonstrate a clear difference in the stratification of the BTNL8_BTNL3-del allele frequency between major continental human populations.

Conclusion

Despite tremendous progress in the field of structural variation, rather few CNVs have been functionally characterized so far. Here, we show clear functional consequences of a new deletion CNV (BTNL8_BTNL3-del) with potentially important implication in the human immune system and in inflammatory and proliferative disorders. In addition, the marked population differences found of BTNL8_BTNL3-del frequencies suggest that this deletion CNV might have evolved under positive selection due to environmental conditions in some populations, with potential phenotypic consequences.

Abstract P3-06-08: Ki-67 mRNA as a predictor for response to neoadjuvant chemotherapy in primary breast cancer

Background: Pathologic complete response (pCR, ypT0/is) is one of the strongest prognostic factors for primary breast cancer (PBC) in the setting of neoadjuvant chemotherapy (NAC). Factors predictive for response to NAC can help to stratify for an individualized therapy. As chemotherapeutic agents are most active in highly proliferative tumors, it was the aim of the present study to evaluate the potential of Ki-67 as a single proliferation marker, quantitatively measured on the mRNA or protein level, to predict response of PBC to NAC.

Material and methods: Pretreatment core cut biopsies from n=72 patients with PBC treated within a randomized phase II trial (1) of anthracylin/taxane based NAC were examined. Immunohistochemistry was performed for the Ki67 antigen on an automated IHC platform (Dako Techmate 500). Ki-67 were assessed either by visual scoring (vIHC) or by quantitative image analysis (qIHC). For quantitative IHC analysis tumor proliferation was analyzed after tumor stroma segmentation using the Aperio Image Analysis toolbox. RNA was extracted from formalin-fixed, paraffin embedded (FFPE) routine biopsies using a bead-based extraction method (STRATIFYER XTRAKT kits). Ki-67, TOP2A and RACGAP1 as well as CALM2 as a house keeping gene were measured via a multiplex quantitative RT-PCR (qPCR). Kaplan-Meier survival estimates, patitioning test and correlation analyses were performed using the SAS JMP® 9.0.0 software.

Results: There was only a moderate correlation between Ki-67 mRNA or Ki-67 measured by immunohistochemistry (IHC) and histologic grade (Spearman r = 0.52 p < 0.0001; r = 0.23 p = 0.033, respectively). Conventional visual scoring and qIHC correlated well (r = 0,78 p < 0,0001), while qPCR and qIHC correlated moderately (r = 0,50 p < 0,0001). For Ki-67 determined by visual scoring of standard IHC there was an optimal discrimination at a cut-off of 20% stained nuclei with regard to chemotherapy response. Yet, the difference between pCR-rates for high and low Ki-67 on IHC was non-significant, with 16.3% and 12.5% pCRs in the IHC Ki-67 high and low group, respectively. For Ki-67 IHC analysed by quantitative image analysis there was optimal cut-off at 35% stained nuclei resulting in 37,5% versus 8,7% pCR rate and 54% of pCRs classified correctly. For qPCR determination, high Ki-67 mRNA expression was associated with a high pCR-rate of 36.4% as opposed to 5.8% in tumors with low Ki-67 mRNA levels and 82% classified correctly.

Conclusion: High Ki-67 mRNA expression measured by RT-qPCR was predictive for the achievement of pCR to NAC and in this respect was superior to Ki-67 determined by vIHC or qIHC. This is consistent with data on Ki-67 IHC as a predictor of pCR on larger neoadjuvant cohorts (1). RT-qPCR based measurements of Ki-67 mRNA ensures an objective and highly reproducible quantification of proliferative activity from FFPE tissue from routine core cut biopsies. As such it seems to be more robust and meaningful compared to protein-based determination of Ki-67 by IHC, both by visual scoring or quantitative image analysis.

1) Schneeweiss et al, Ann Oncol 2011 2) Fasching et al., BMC Cancer 2011

Citation Information: Cancer Res 2012;72(24 Suppl):Abstract nr P3-06-08.

The role of neoadjuvant chemotherapy in the management of primary breast cancer

Neoadjuvant chemotherapy for primary breast cancer is the gold standard in the treatment of locally advanced, inoperable breast cancer, but based on a large body of evidence has become a standard treatment option for patients with operable disease, who are clear candidates for adjuvant chemotherapy. Neoadjuvant chemotherapy aims at reducing mortality and improving surgical options and offers an in vivo chemosensitivity testing at the same time. It is the ideal setting for clinical and translational research. Administering chemotherapy before surgery raises some important issues concerning the choice of specific treatment regimens as well as the management of the axilla and postoperative radiotherapy. A reliable high quality diagnostic and pathological work-up is mandatory for an ideal tailoring of neoadjuvant chemotherapy. This review gives an outline of the state-of-the-art management of primary breast cancer in the setting of neoadjuvant chemotherapy.

Active transport of the ubiquitin ligase MID1 along the microtubules is regulated by protein phosphatase 2A

Mutations in the MID1 protein have been found in patients with Opitz BBB/G syndrome (OS), which is characterised by multiple malformations of the ventral midline. MID1 is a microtubule-associated protein that stabilizes microtubules and, in association with the regulatory subunit of protein phosphatase 2A (PP2A), alpha4, provides ubiquitin ligase activity for the ubiquitin-specific modification of PP2A. Using Fluorescence Recovery After Photobleaching (FRAP) technology, we show here that MID1 is actively and bi-directionally transported along the microtubules, and that this movement is directly linked to its MAP kinase and PP2A-mediated phosphorylation status. Intact transport depends on both kinesins and dyneins and is inhibited upon colcemide treatments. MID1 proteins carrying missense mutations in the alpha4 binding domain still bind the microtubules but cannot be actively transported. Likewise, knock-down of the alpha4 protein, inhibition of PP2A activity by okadaic acid and fostriecin or the simulation of permanent phosphorylation at Ser96 in MID1 stop the migration of MID1-GFP, while preserving its microtubule-association. In summary, our data uncover an unexpected and novel function for PP2A, its regulatory subunit alpha4 and PP2A/alpha4/mTOR signaling in the active transport of the MID1 ubiquitin ligase complex along the cytoskeleton. Furthermore, a failure in the microtubule directed transport of this protein complex would be an attractive mechanism underlying the pathogenesis of OS in patients with B-box1 mutations.

The Opitz syndrome gene product MID1 assembles a microtubule-associated ribonucleoprotein complex

Opitz BBB/G syndrome (OS) is a heterogenous malformation syndrome mainly characterised by hypertelorism and hypospadias. In addition, patients may present with several other defects of the ventral midline such as cleft lip and palate and congenital heart defects. The syndrome-causing gene encodes the X-linked E3 ubiquitin ligase MID1 that mediates ubiquitin-specific modification and degradation of the catalytic subunit of the translation regulator protein phosphatase 2A (PP2A). Here, we show that the MID1 protein also associates with elongation factor 1alpha (EF-1alpha) and several other proteins involved in mRNA transport and translation, including RACK1, Annexin A2, Nucleophosmin and proteins of the small ribosomal subunits. Mutant MID1 proteins as found in OS patients lose the ability to interact with EF-1alpha. The composition of the MID1 protein complex was determined by several independent methods: (1) yeast two-hybrid screening and (2) immunofluorescence, (3) a biochemical approach involving affinity purification of the complex, (4) co-fractionation in a microtubule assembly assay and (5) immunoprecipitation. Moreover, we show that the cytoskeleton-bound MID1/translation factor complex specifically associates with G- and U-rich RNAs and incorporates MID1 mRNA, thus forming a microtubule-associated ribonucleoprotein (RNP) complex. Our data suggest a novel function of the OS gene product in directing translational control to the cytoskeleton. The dysfunction of this mechanism would lead to malfunction of microtubule-associated protein translation and to the development of OS.

Vascular tissue engineering with magnetic nanoparticles: seeing deeper

The endothelium bares a paramount therapeutic and diagnostic significance in vascular disease. The current work presents a novel strategy based on the use of superparamagnetic nanoparticles to obtain an endothelial cell lining on the luminal surface of vascular conduits, which can be detected non-invasively in a clinical Magnetic Resonance Imaging (MRI) scanner. Human umbilical vein endothelial cells (HUVECs) were prelabeled with clinically approved superparamagnetic nanoparticles. Cell viability and eNOS expression were not affected by the labelling procedure. Magnetically labelled cells were delivered onto the lumen of a PTFE tubular graft by a customised electromagnet. The endothelium was detected in a 1,5T MRI scanner. Magnetic cell delivery provides an efficient technique to seed tubular scaffolds enabling the non-invasive depiction of the cells from the substrate, thus providing a reliable tool to assess the quality of cell delivery procedures.

Effect of different gamma-irradiation doses on cytotoxicity and material properties of porous polyether-urethane polymer

Biomaterials respond to sterilization methods differently. Steam sterilization might decrease the performance of thermoplastic polyether-urethane (TPU); however, the effect of different gamma-radiation doses on this polymer is contradictory in present literature. The purpose of this study was to investigate the differences between irradiative doses in comparison with steam sterilization on a porous TPU scaffold produced by a new processing method. No significant differences in the surface chemical structure were found with attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR) analysis when comparing with the sterilization methods. The molecular weight (M(w)) had a net increase from 11.5 +/- 0.039 to 13.2 +/- 0.072 kDa by gamma-sterilization from 10 to 60 kGy. The samples that were irradiated (>60 kGy) had also an increase in polydispersity index (PDI; 1.45 +/- 0.007) in comparison with the nonsterile ones (1.31 +/- 0.017), which indicate branching. Liquid chromatography/mass spectroscopy (LC/MS) analysis showed that there was a correlation between the concentration of the breakdown product, methyl dianiline, and cytotoxicity. The concentration of this compound was found to be four times higher in steam-sterilized sample (1.3 +/- 0.01 ppb) compared with that of the polymer sample gamma-sterilized at 10 kGy (0.3 +/- 0.01 ppb). The cytotoxicity of TPU was found to decrease with higher radiation doses, and was significantly higher for the steam-sterilized samples. It is recommended that TPU produced with the described foaming method should be sterilized by gamma-irradiation at 25 kGy or higher doses.

Das STEMMAT-Projekt als Teil der Gesundheitsinitiative BayernAktiv: Adulte Stammzellen aus Nabelschnur und -blut als Alternative zur embryonalen Stammzellforschung

Adult stem cells from umbilical cord and cord blood are an interesting alternative to embryonic stem cells because such research is commonly recognized as ethical undisputed and many aspects are still insufficiently investigated. In the context of the STEMMAT research project (STEM = Stem Cell and MAT = Material) different aspects of stem cells from umbilical cord and cord blood are investigated, to improve basic science understanding and potentially leading someday to a clinical application.

A novel processing method for injection-molded polyether–urethane scaffolds. Part 2: Cellular interactions

A large-scale scaffold processing method with injection molding has been successfully developed. Water was used as a foaming agent for the new technique. NaCl was used as a porogen to achieve an open-cell structure. Organic solvents, which are common foaming agents for polyurethane, where not used. Toxic remains in the polymer were therefore prevented. Biocompatibility tested gave a mean optical density of 81% from WST-1 proliferation assay. In comparison to the previously study processing method, hot pressing (Haugen H, Ried V, Brunner M, Will J, Wintermantel E. J Mater Sci: Mater Med2004;15:343-346), the current scaffolds had an increase of 20% of the mean optical density. Cell seeding showed that human fibroblasts adhered to the surface and proliferated. The spread of the adhered fibroblasts was uniform on the surface. A quantitative MTT analysis proved that there was a significant (p < 0.01) increase in the OD level after 7 and 14 days of incubation. This cell layer thickened with increased incubation time from 7 to 14 days (p < 0.05) and had typical fibroblast morphology.

Funktioneller Gewebe- und Organersatz mit postnatalen Stammzellen

Postnatal stem cells play a decisive role in cell-based therapies due to their high proliferation activity and functional plasticity. On the one hand, basic research in cell biological processes of adult stem cells is crucial in order to establish them as therapeutic tools. On the other hand, development and enhancements of appropriate techniques are required: we need to establish defined technologies for extraction and differentiation of stem cells and to develop adequate cell carrier devices, scaffolds, and bioreactors for in vitro purposes. Furthermore, it is an interdisciplinary challenge to consider logistical aspects concerning isolation, transport, and storage of stem cells in order to use them in a wide range of activities in regenerative medicine. In this review we present the current methods of work and research on adult stem cells. We explain their therapeutic use and define requirements for future technological developments for work with postnatal stem cells.

Umbilical Cord Stromal Cells (UCSC)

The identification of appropriate cell types is necessary to establish cell-based therapies in regenerative medicine. These cell types must (1) be available in an appropriate amount, (2) be easy to obtain, (3) be sufficiently expandable in vitro, and (4) fit to or at least be able to differentiate into the required cell type. Since the umbilical cord is available without any intervention and represents a notable amount of tissue, we consider it to be a promising source for isolating cells for cell-based therapies. This study demonstrates that umbilical cord stromal cells (UCSC), the connective tissue cells of the umbilical cord, can be isolated in sufficient quantities and be well expanded. UCSC feature phenotypic plasticity and thus are functionally similar to stem cells. UCSC can be differentiated into cells with osteoblastic properties (expression of alkaline phosphatase, formation of bone nodules). It is concluded that the umbilical cord should no longer be regarded as valueless tissue and be unthinkingly discarded. Instead, it should be considered a valuable resource for the isolation of potent cells for cell-based therapies, especially for treatment of bone defects.

Gez�chtetes Knorpelgewebe in einem pr�fabrizierten, mikrovaskul�ren Lappen

INTRODUCTION

In reconstructive surgery, the integration of tissue-engineered cartilage in a prefabricated free flap may make it possible to generate flaps combining a variety of tissue components to meet the special requirements of a particular defect. The aim of the present study was to establish the technique of prefabricating a microvascular free flap by implanting a vessel loop under a skin flap in a rabbit model. The second aim was to gather experience with prelaminating the flap with autologous tissue-engineered cartilage in terms of matrix development, inflammatory reaction and host-tissue interaction.

METHODS

The microvascular flap was created by implanting a vessel loop under a random pattern abdominal skin flap. The tissue-engineered cartilage constructs were made by isolating chondrocytes from auricular biopsies. Following a period of amplification, the cells were seeded onto a non-woven scaffold made of a hyaluronic acid derivative and cultivated for 2-3 weeks. One cell-biomaterial construct was placed beneath the prefabricated flap, and the others were placed subcutaneously under the abdominal skin and intermuscularly at the lower extremity. In addition, a biomaterial sample without cells was placed subcutaneously as a control. All implanted specimens were left in position for 6 or 12 weeks. After explantation, the specimens were examined by histological and immunohistological methods. The prefabricated flap was analyzed by angiography.

RESULTS

The prefabricated flaps showed a well-developed network of blood vessels formed by neovascularization between the implanted vessel loop and the original random-pattern blood supply. The tissue-engineered constructs remained stable in size and showed signs of tissue similar to hyaline cartilage, as evidenced by the expression of cartilage-specific collagen type II and proteoglycans. No hints of inflammatory reactions were observed.

CONCLUSION

These results show the potential of prefabricated flaps as custom-made flaps for reconstructive surgery in difficult circumstances, more or less independent of anatomical prerequisites. Cartilage tissue engineering provides a 3-dimensional structure with minimal donor-site morbidity.

Clinical aspects and strategy for biomaterial engineering of an auricle based on three-dimensional stereolithography

At the present time, the partial and/or complete reconstruction of an auricle from autologous rib cartilage is one of most widely published techniques. In the field of tissue engineering, different techniques have been described to generate cartilage tissue using isolated chondrocytes. The basis of these tissue-engineering techniques is bioresorbable or non-bioresorbable biomaterials, which serve as a three-dimensional cell carrier. Tissue engineering of an auricle requires preformed bioresorbable biomaterials designed to fit the form of a patient's auricular defect. Three-dimensional imaging acquired from computed tomography scans or laser surface scanning has become an important tool in modern medicine. This study represents the preoperative procedures for the reconstruction of an auricle through tissue engineering in accordance with the clinical aspects. Hyaff 11, a hyaluronic acid derivative, was used as a three-dimensional cell carrier for isolated human nasoseptal chondrocytes. The chondrocytes were amplified in a conventional monolayer culture before the cells were seeded on a hyaluronic non-woven mesh and cultured in vitro for 4 weeks. The chondrogenic potential of human nasal chondrocytes in Hyaff 11 was investigated by confocal laser scanning microscopy, histology (toluidine blue) and immunohistochemistry (collagen type II). Computer-aided design (CAD) and manufacture of an auricle model with stereolithographical methods were used for the prefabrication of a bioresorbable three-dimensional cell carrier designed in the form of a patient's auricular defect. The cell carrier used was Hyaff 11, a fully benzyl-esterified hyaluronic acid derivative. Confocal laser scanning microscopy has shown good cell attachment, a homogenous distribution of amplified chondrocytes and a viability of more than 90%. After 4 weeks in vitro culture the human nasoseptal chondrocytes synthesized new cartilage with the expression of cartilage-specific collagen type II. In order to shape a patient's designed scaffold the auricle model was fitted exactly and symetrically to the contralateral side. Subsequently, the mirror image patient-specific model was used to prepare an identical scaffold model made of a fully benzyl-esterified hyaluronic acid derivative. The bioresorbable scaffold that was produced gave a satisfactory representation of auricle structure. Bioresorbable preformed biomaterials in the form of a patient's auricle defect represent an important prerequisite for the tissue engineering of autologous auricle grafts. Hyaff 11 seems to be a promising material for tissue engineering of cartilage transplants, and the application of this approach will improve conventional reconstructive surgery in the future.

[Mesenchymal stem cells--a new pathway for tissue engineering in reconstructive surgery]

INTRODUCTION

Mesenchymal stem cells (MSC) have the capacity to differentiate into chondrocytes with the synthesis of cartilage. This report presents the use of human adult bone marrow derived mesenchymal stem cells for tissue engineering of autologous cartilage grafts.

METHODS

Human bone marrow aspirates were obtained from the iliac crest and fractionated on a Percoll gradient. The isolated hMSC were plated at 20 x 10 (6) cells per 100 mm (2) culture dish. After 21 days in culture at 37 degrees C with 5 % CO 2, the adherent multiplied MSC were trypsinized, counted, and tested for viability by trypan blue assay. The hMSCs were loaded into a sterile 15 ml polypropylene tube (0.5 Mio cells/ml) and centrifuged on the bottom of the tube at 500 g for 5 minutes. The MSC were cultivated for 3 weeks in vitro in a specific chondrogenetic medium composed of Dulbecco's Modified Eagles Medium-High Glucose supplemented with 10 ng/ml transforming growth factor-beta 1, 1 % ITS-Premix medium, 80 micro M ascorbic acid, and 100 nM dexamethasone.

RESULTS

Histological and immunohistochemical studies performed after 3 weeks in three dimensional culture demonstrated the expression of cartilage specific collagen type II and X as well as proteoglycans.

CONCLUSION

Human adult mesenchymal stem cells derived from bone marrow aspirates have the ability to differentiate into chondrocytes under specific culture conditions by growth factors. The use of adult mesenchymal stem cells may be a promising tool for tissue engineering of autologous cartilage grafts in reconstructive surgery in the future.

[Microtia: technique for external ear reconstruction with autologous rib cartilage]

Various methods for treatment of classic microtia are known. Beside a prosthesis, the most common way of auricle reconstruction is the use of autogenous rib cartilage; a process that requires two to three operations. In the first operation, rib cartilage is harvested from the 6th to the 9th rib. The base of the framework is the 6th and 7th rib cartilage which is taken under preservation of the synchondrosis. To mimic a 3-dimensional structure, the triangular fossa and scapha are carved into the groundplate and the 8th rib is fixed as a helical rim. After optimising the framework, it is placed in a subcutaneous pocket on the mastoid plane. In a second operation, approximately three months later, the auriculocephalic angle is reconstructed with a cartilage wedge, which is covered by a temporalis fascia flap and split skin-graft from the hairbearing skull. Commonly, a third operation is needed for minor refinements. Currently, autogenous rib cartilage is the ideal material available for ear reconstruction resulting in an excellent cosmetical outcome, although harvesting of the cartilage causes a specific donor-site morbidity. Operations improving the hearing ability by building up the external hearing channel and middle ear are mainly done in cases of bilateral microtia. Ear reconstruction with autogenous rib cartilage produces a replicable aesthetic result. The patients should be at least eight years old.

Screening for Aspergillus spp. using polymerase chain reaction of whole blood samples from patients with haematological malignancies

Sensitive screening for Aspergillus spp. using polymerase chain reaction (PCR) of whole blood samples in patients with haematological disorders has not been performed to date. In a 2-year study, 121 patients admitted to the University Hospital of Innsbruck for cancer chemotherapy without clinical signs of fungal infection were prospectively screened for Aspergillus spp. In 28 out of 121 (23%) patients, Aspergillus DNAaemia was detected. Of these patients, 16 (57%) were positive only once for Aspergillus DNA, but positivity was never associated with invasive aspergillosis. PCR positive episodes were short and resolved without antifungal treatment. Five patients (18%) had intermittent PCR positive results. Seven (25%) patients presented at least two consecutive positive PCR results; one of these patients developed invasive aspergillosis and another two were strongly suspected as having aspergillosis. Based on the criteria of the European Organization for Research and Treatment of Cancer case definitions, sensitivity and specificity of serial PCR monitoring were 75% and 96%. Positive PCR results became negative shortly after commencement of antifungal treatment, but the changes did not correlate with clinical responsiveness to treatment in three patients. Our results indicate the potential usefulness of PCR for screening for Aspergillus spp. in patients at risk, but without antifungal treatment.

Relapsing polychondritis: a course over 20 years with cerebral involvement

Relapsing polychondritis is a chronic inflammatory disease associated with an autoimmune disorder in cartilaginous tissue, eyes, labyrinth, blood vessels, and central nervous system. We describe a 75-year-old woman who presented with a 20-year history of dyspnea, inspiratory stridor, and polyarthritis. She developed dysmorphism of both ears and a saddle nose approximately 10 years earlier. Subsequently, she suffered from hearing loss and a tremor. A T2-weighted magnetic resonance imaging scan of the brain revealed multiple, spotted signal intensities. Immunohistochemical analysis of a serum sample showed antibodies to cartilaginous tissue, which were further identified on immunoblotting as antibodies to type II collagen. The extremely prolonged course of disease (>20 years) until a correct diagnosis was made is remarkable. Also, cerebral involvement, which was most likely caused by cerebral angiitis, and which, to our knowledge, has never previously been reported in this form, was detected. Arch Otolaryngol Head Neck Surg. 2000;126:1495-1498

[Highly malignant T-cell non-Hodgkin lymphoma (nasal type) of the hard palate]

The monomorphic clinical aspect of destructive mid-face lesions is characterised by inflammation, induration and granulomatous transformation. This feature can be caused by various infections, toxical noxa, Wegener's Granulomatosis and different neoplasms. The case of a 19 year old patient with EBV associated nasal type T-cell lymphoma located at the hard palate is presented. The diagnostic approach and difficulties in diagnosing this entity assessing by using multiple biopsies, serological and molecularbiological detection of EBV association and immunohistochemistry for atypic T-cells are elucidated. In the presented case the treatment with chemotherapy and irradiation following a well-defined therapy concept leaded to a three year recurrence-free survival so far. The comparison of the key-histological findings and the major differential diagnoses is mandatory to establish the final diagnosis of lymphoma. This is the basement for treating this disease with combined chemotherapy and irradiation for optimizing survival.

[Subcutaneous preservation of an amputated auricle. Morphological changes]

BACKGROUND

Microsurgical replantation of an avulsed auricle remains a challenge in reconstructive surgery. Secondary reconstruction of a traumatic lost auricle is usually performed using a costal cartilage framework according to well documented techniques or with a prosthesis. In order to minimize donor-site morbidity, various efforts can be undertaken to preserve the amputated auricle by implanting the de-epithelialized cartilage framework in a subcutaneous pocket on the surface of the mastoid. Where preservation is successful, this original cartilage could be used for reconstructive treatment.

PATIENT AND RESULTS

This study describes the histologic and immunohistologic changes in a complete traumatic avulsion of the auricle with subsequent cartilage conservation for eight months within a skin pocket. Trauma, preparation and preservation were accompanied by morphologic changes that included generation of local ossification centers and infiltration of fibrous tissue. We compared the macroscopic and microscopic morphology of the amputated part to native elastic cartilage following maximal denutrition and temporary heterotopic implantation in conjunction with atypical tension and pressure properties of the retroauricular pocket.

CONCLUSION

In this case, the limited success of cartilage conservation in the subcutaneous pocket required conventional auricle reconstruction with autologous costal cartilage.

Tissue-engineered cartilage using serially passaged articular chondrocytes. Chondrocytes in alginate, combined in vivo with a synthetic (E210) or biologic biodegradable carrier (DBM)

In vitro multiplication of isolated autologous chondrocytes is required to obtain an adequate number of cells to generate neo-cartilage, but is known to induce cell-dedifferentiation. The aim of this study was to investigate whether multiplied chondrocytes can be used to generate neo-cartilage in vivo. Adult bovine articular chondrocytes, of various differentiation stages, were suspended in alginate at densities of 10 or 50 million/ml, either directly after isolation (P0) or after multiplication in monolayer for one (P1) or three passages (P3). Alginate with cells was seeded in demineralized bovine bone matrix (DBM) or a fleece of polylactic/polyglycolic acid (E210) and implanted in nude mice for 8 weeks. The newly formed tissue was evaluated by Alcian Blue and immunohistochemical staining for collagen type-II and type-I. Structural homogeneity of the tissue, composed of freshly isolated as well as serially passaged cells, was found to be enhanced by high-density seeding (50 million/ml) and the use of E210 as a carrier. The percentage of collagen type-II positive staining P3-cells was generally higher when E210 was used as a carrier. Furthermore, seeding P3-chondrocytes at the highest density (50 million/ml) enhanced collagen type-II expression. This study shows promising possibilities to generate structurally regular neo-cartilage using multiplied chondrocytes in alginate in combination with a fleece of polylactic/polyglycolic acid.

Behavior of tissue-engineered human cartilage after transplantation into nude mice

Cartilage lacks the ability to regenerate structural defects. Therefore, autologous grafting has been used routinely to replace cartilaginous lesions. Because tissue engineering of human cartilage with the help of bioresorbable polymer scaffolds is possible in experimental models, the demand for the clinical application grows. In this study we present an analysis of the behavior of transplants made of human chondrocyte pools, agarose and the resorbable polymer scaffold Ethisorb and a preliminary comparison with transplants made of single patients' cells and Ethisorb but without the additional ingredient agarose. Chondrocytes were isolated from the matrix of human septal cartilage by enzymatic digestion. The pool cells were kept in monolayer culture for 2 weeks, the single patients' cells for 3-4 weeks. Chondrocyte pools were suspended in agarose and seeded into the resorbable polymer scaffold Ethisorb. Single patients' cells were seeded without agarose. All cell-polymer constructs were kept in perfusion culture for 10-14 days and transplanted subcutaneously into thymusaplastic nude mice. Additionally we implanted Ethisorb fleeces embedded in agarose without chondrocytes. After 6, 12 and 24 weeks the animals were sacrificed and the specimens were explanted and analyzed histochemically and immunohistochemically. Polymer scaffolds not seeded with chondrocytes did not show cartilage formation. Resorption was complete after 12 weeks in vivo. Transplants from cell pools remained mechanically stable over 24 weeks apart from four transplants that were resorbed completely. Cartilage formation was observed in all pool-specimens with the presence of chondronic structures and a homogeneous matrix containing hyaline cartilage-specific matrix molecules such as collagen type II. Single patients' transplants showed hyaline cartilage matrix synthesis and mechanical stability as well. Chondrocyte pools are a suitable method to study cartilage engineering of human cells in vitro and in vivo in experimental models. Under clinical conditions it is, however, necessary to study the generation of cartilage from single patients' cells. We showed that it is possible without additional ingredients such as agarose. However, variations in the preliminary results show that the clinical application with human cells is more difficult than one would expect when using human chondrocyte pools. Further studies need to be performed to find out which individual factors influence the in vitro engineered cartilage's fate in vivo.

Cartilage reconstruction in head and neck surgery: comparison of resorbable polymer scaffolds for tissue engineering of human septal cartilage

New cell culture techniques raise the possibility of creating cartilage in vitro with the help of tissue engineering. In this study, we compared two resorbable nonwoven cell scaffolds, a polyglycolic acid/poly-L-lactic acid (PGA/PLLA) (90/10) copolymer (Ethisorb) and pure PLLA (V 7-2), with different degradation characteristics in their aptitude for cartilage reconstruction. Chondrocytes were isolated enzymatically from human septal cartilage. The single cells were resuspended in agarose and transferred into the polymer scaffolds to create mechanical stability and retain the chondrocyte-specific phenotype. The cell-polymer constructs were then kept in perfusion culture for 1 week prior to subcutaneous transplantation into thymusaplastic nude mice. After 6, 12, and 24 weeks, the specimens were explanted and analyzed histochemically on the presence of collagen (azan staining), proteoglycans (Alcian blue staining), and calcification areas (von Kossa staining). Furthermore, different collagen types (collagen type I, which is found in most tissues, but not in hyaline cartilage matrix; and collagen type II, which is cartilage specific) were differentiated immunohistochemically by the indirect immunoperoxidase technique. Vascular ingrowth was investigated by a factor VIII antibody, which is a endothelial marker. Quantification of several matrix components was performed using the software Photoshop. Significant differences were found between both nonwoven structures concerning matrix synthesis and matrix quality as well as vascular ingrowth. Ethisorb, with a degradation time of approximately 3 weeks in vitro, showed no significant differences from normal human septal cartilage in the amount of collagen types I and II 24 weeks after transplantation. Thin fibrous tissue layers containing blood vessels encapsulated the transplants. V 7-2 constructs, which did not show strong signs of degradation even 24 weeks after transplantation, contained remarkably smaller amounts of cartilage-specific matrix components. At the same time, there was vascular ingrowth even in central parts of the transplants. In conclusion, polymer scaffolds with a short degradation time are suitable materials for the development of cartilage matrix products, while longer stability seems to inhibit matrix synthesis. Thus, in vitro engineering of human cartilage can result in a cartilage-like tissue when appropriate nonwovens are used. Therefore, this method could be the ideal cartilage replacement method without the risk of infection and with the possibility of reconstructing large defects with different configurations.

Cartilage tissue engineering with novel nonwoven structured biomaterial based on hyaluronic acid benzyl ester

The aim of this study was to investigate the possibility of using the benzyl ester of hyaluronic acid (HYAFF 11), a recently developed semisynthetic resorbable material, as a scaffold for the culture of human nasoseptal chondrocytes in tissue-engineering procedures of cartilage reconstruction. Different techniques such as immunohistochemistry, scanning electron microscopy, and confocal laser scanning microscopy were used to study the behavior, morphology, and phenotype expression of the chondrocytes, which were initially expanded and then seeded on the material. The nonwoven cell carrier allowed good viability and adhesivity of the cells without any surface treatment with additional substances. Furthermore, the cultured cells expressed cartilage-specific collagen type II, indicating that they were able to redifferentiate within the scaffold of HYAFF 11 and were able to retain a chondrocyte phenotype even after a long period of in vitro conditions. Nevertheless, the expression of collagen type I, which was produced by dedifferentiated or incompletely redifferentiated chondrocytes, was noticeable. Additional data were obtained by subcutaneous implantation of samples seeded with human cells in the in vivo model of the athymic nude mouse. The results after 1 month revealed the development of tissue similar to hyaline cartilage. This study is promising for the use of this scaffold for tissue engineering of cartilage replacements.

Transitional stages in the development of the rabbit renal collecting duct

The collecting duct (CD) epithelium of the mammalian kidney is an extraordinary structure with respect to its functional changes during development and its heterogeneous composition when matured. All of the different nephron epithelia of the mammalian kidney consist of one single cell type. In contrast, the differentiated CD is composed of at least three distinct cell types [principal, alpha intercalated-, and beta intercalated cells] that are responsible for the multiple physiological functions of this kidney compartment. During development the function of the CD changes: initially, the CD ampulla serves as an embryonic inducer, while the matured epithelium plays a key role in maintaining the homeostasis of body fluids. At present the process of CD maturation is not well understood. Neither the time course of development nor the morphogenic factors leading to the heterogeneously composed epithelium are known. In the present study the differentiation of the CD epithelium was investigated using newly developed monoclonal antibodies and well-characterized antisera. The morphological changes induced during differentiation were monitored by immunohistochemistry and scanning electron microscopy. The experiments were performed on neonatal and adult rabbit kidneys. Results obtained by light microscopical techniques and scanning electron microscopy revealed that the ampullary tip can be distinguished from the ampullary neck, as well as from the maturing CD. A number of proteins that were not detectable in the ampulla were detected in the neonatal CD and were found at even higher concentrations in the adult CD (PCD8, chloride/bicarbonate exchanger). Other proteins (PCD9) were downregulated during differentiation. For the first time the transient character of the differentiation stage of the neonatal CD could be demonstrated unequivocally. Furthermore, considerable heterogeneity in protein expression patterns (PCD6 and PCD9) was demonstrated within the beta IC cell population of the mature CD.

Tissue engineering of autologous cartilage transplants for rhinology

In reconstructive surgery there is increasing demand for cartilage transplants to fill defects, especially nose and/or outer ear defects. Tissue engineering is one of the most modern pathways to generate autologous cartilage transplants. Isolated chondrocytes obtained from a tiny patient's biopsy were seeded on bioresorbable preshaped cell carriers to provide a 3-dimensional cell arrangement as in vivo. The combined use of these cell carriers in form of a non-woven mesh and a constant medium perfusion was performed to generate a cartilage-like cell-polymer-construct, which was finally subcutanously implanted in nude mice for full maturation. After explantation of 6 months, expression of cartilage specific extracellular matrix molecules was obvious by using histochemical and immunohistochemical methods. These data show that tissue engineering with isolated multiplied human chondrocytes from a tiny biopsy seeded on bioresorbable polymer is a promising system to generate autologous cartilage transplants for replacements in reconstructive surgery.

PCDAmp1, a new antigen at the interface of the embryonic collecting duct epithelium and the nephrogenic mesenchyme

In the neonatal rabbit kidney nephrogenesis is not yet terminated. The ampullar collecting duct epithelium acts as an inducer that generates the nephron anlagen, however, to date the morphogenic mechanisms involved are unknown. A presupposition for successful nephron induction is the close tissue interaction between the basal aspect of the ampullar collecting duct epithelium and the surrounding mesenchyme. To gain new insights in this area we raised monoclonal antibodies (mabs), to identify specific structures localized at the tissue interface. With the generated mab CDAmp1 we found an intensive immunohistochemical reaction between the basal aspect of the ampullar collecting duct epithelium and the mesenchyme. The label was most concentrated at the ampullar tip and continuously decreased in the shaft region. In the maturing collecting duct of the neonatal kidney and in the adult renal collecting duct no immunohistochemical reaction was found. The binding pattern of mab CDAmp1 is different from that of all known collecting duct cell markers and from antibodies against known basement membrane compounds such as laminin or collagen type IV. Under in vitro conditions immunoreactivity with mab CDAmp1 was obtained using embryonic collecting duct epithelia and perfusion culture. The antigen was present in specimens treated with Iscove's modified Dulbecco's Medium (IMDM) containing 10% fetal bovine serum. Omittance of serum or hormonal treatment with aldosterone, insulin or vitamin D3 led to the disappearance of the newly detected antigen, while characteristics of the differentiated collecting duct cells were up-regulated. We conclude that the expression of PCDAmp1 is a characteristic feature of the embryonic parts of the collecting duct epithelium. It may play a pivotal role during nephron induction.

[Realistic imaging of cell systems using confocal laser scanning microscopy exemplified by 3-dimensional chondrocyte culture]

BACKGROUND

We have developed a three-dimensional model for tissue engineering of cartilage. Chondrocytes were isolated and first multiplied in conventional monolayer cultures. Then the cells are seeded with or without agarose on special absorbable scaffolds that provided stability and enabled three-dimensional cell distribution of the tissue-engineered cartilage. The aim of the study was to investigate the possibility of avoiding agarose in tissue engineering because of the potential risk of causing an inflammatory process in later human implantation.

METHOD

For the first time we investigated cell distribution combined with vitality directly in the cell carrier under the conditions described by using confocal laser-scanning microscopy. Working with unfixed cells, this method enables the reconstruction of three-dimensional cell cultures with suitable cell markers that closely simulates the physiologic situation, thereby exceeding each other method.

RESULTS

It was evident that agarose had no positive effect on cell distribution and vitality.

CONCLUSION

Further experiments concerning the effect of agarose on synthesis of cartilage-specific matrix are in progress.

Culture of embryonic renal collecting duct epithelia in a gradient container

During organogenesis the ampullar epithelium of the renal collecting duct acts as an inducer which generates all of the nephron anlagen. As development proceeds, one part of the collecting duct cells in the ampullar tip retain their inducer capability, while others develop into the functional epithelium consisting of principal and intercalated (IC) cells. The events leading from the embryonic inducer to the mature tissue are unknown. We investigated the maturation of embryonic collecting duct epithelium derived from neonatal rabbit kidney under in vitro conditions. To prevent dedifferentiation the epithelia were cultured on kidney-specific support material within a tissue carrier. Apical and basal compartments of the epithelia were simulated in a gradient culture container. The two sides of the epithelium were each constantly perfused with a different medium. During the 14-day incubation the tissue was not subcultured. The development of collecting duct cell features was investigated with morphological and immunohistochemical methods. Both light and electron microscopy revealed morphologically intact epithelia following gradient culture. The polarized cells rested on a uniformly developed basement membrane. The continuous application of aldosterone during the culture modulated the development of collecting duct cell characteristics. Both basal and luminal administration of aldosterone initiated differentiation in the embryonic epithelia. Using the sodium (Na) channel blocker amiloride, it was demonstrated that Na channels are involved in the differentiation of the IC cell phenotype.

[Vital long-term preservation of human gingiva in perfusion culture]

Perfusion culture offers the advantage of keeping gingiva alive for a long time as an stable explant according to cell biological parameters. To investigate the suitability of cultured human gingival explants for transplantations the biopsies were put into a newly developed perfusion chamber and cultured for at least 21 days. Gingiva explants were derived from healthy donors undergoing surgical removal of molar teeth. The tissue pieces were cultured without prior proteolytic desintegration or subculture. Immediately after excision a morphological and immunohistochemical analysis of the tissue was carried out and the distribution pattern of cytokeratin and vimentin was examined. Gingival explants cultured for 7, 14 and 21 days in serum-free keratinocyte growth medium in perfusion culture were analyzed in the same way. The morphology of the cultured explant (21 days) was well preserved from stratum basale up to stratum corneum. As proved by immunohistochemical incubation with antibodies to CK 5/6, CK 14 and CK 19, a tissue-specific cytokeratin (CK) expression pattern was maintained during the whole perfusion period. After 7 days of culture vimentin was synthesized in the fibroblast layer and was found in small quantities in each layer of the epithelium. In contrast to conventional cultures, where dissociation of the tissue and a subculture interruption is usually needed for long-term culture, this is not necessary for perfusion cultured tissue. The use of perfusion-cultured gingival explants as autogenous transplants is investigated herein.

Endotoxin-inducible granulocyte-mediated hepatocytotoxicity requires adhesion and serine protease release

In primary cultures of Kupffer cells and hepatocytes, human granulocytes potentiated toxicity of endotoxin about 1000-fold. Granulocyte elastase activity was found to correlate with toxicity. The serine protease inhibitors alpha1-antitrypsin, eglin C, and aprotinin protected against toxicity. Tumor necrosis factor-alpha (TNF-alpha) induced cytotoxicity and elastase release, whereas neutralization of TNF-alpha blocked both events. We conclude that TNF-alpha formed by Kupffer cells activates granulocytes. Experiments in cultures where cells were separated by membranes permeable to mediators indicated that cell contact is needed for toxicity. Scanning electron microscopy showed granulocytes adhering to and interdigitating with hepatocytes. Using liver cells from ICAM-1-deficient mice had no effect on toxicity. However, neutralizing CD31 inhibited toxicity and elastase release but not granulocyte adhesion. Our findings demonstrate that adhesion of granulocytes is a necessary but not sufficient condition for the synergistic interaction of endotoxin-stimulated liver macrophages and granulocytes in the proteolytic killing of hepatocytes.

Approach to an organo-typical environment for cultured cells and tissues

If cells or tissues are taken out of an organ and put in culture, normally they lose morphological, physiological and biochemical features. This dedifferentiation process starts during the isolation procedure and continues during the whole culture period. It is caused by the stagnant liquid condition and the inadequate anchorage of cells at the bottom of tissue culture plasticware. The use of filters as basement membrane substitutes and the coating of cultureware with extracellular matrix proteins improve the environmental factors for cultured cells but do not consider the paracrine influence of cytokines or the nutritional needs of individual cell types. To limit cellular dedifferentiation in culture, we constructed a new system, which adapts, as far as possible, cell and tissue cultures to an organo-typical environment. The system is based on a compatible cell carrier arrangement, which allows individual selection of supports for optimal cell anchorage and differentiation. The cell carriers are placed in a newly constructed container, which is permanently perfused with fresh culture medium. The system runs outside an incubator with simple laboratory tools; only a peristaltic pump, a warming table and pH-stabilized media are necessary. Without any subculturing, acute and chronic influences of drugs or the quality of medical implantation grafts can be studied over months.

Development of renal podocytes cultured under medium perifusion

BACKGROUND

In the past, podocytes have been described as highly susceptible to dedifferentiation under cell culture. Whether this process resulted from insufficient culture conditions or whether it was a consequence of missing cellular interactions remained unclear. A further reason could be that podocytes within the maturing kidney are irreversibly growth-arrested at a very early point of development because proliferating cells have been detected at the S-shaped body stage but not at the capillary loop stage or in the maturing glomeruli. These were important reasons that hindered the establishment of podocyte cell culture systems.

EXPERIMENTAL DESIGN

The aim of our present study was to culture podocytes under the most organotypic conditions possible to maintain typical cellular characteristics. Cortex explants of neonatal rabbit kidneys consisting of nephrogenic tissue were used as a source for podocytes. No serum additives were given for the whole culture period of 13 days. An organ-specific environment was obtained by keeping the podocytes within the surrounding renal tissue and by ensuring a permanent exchange of medium.

RESULTS

mAb were used to characterize podocytes and the other glomerular cell types. Cultured podocytes and parietal cells of Bowman's capsule were identified by EnPo 1. Ks 19.2.105, a marker for cytokeratin 19, was used to discriminate among these epithelial cells because cytokeratin 19 is expressed by the parietal cells of Bowman's capsule but not by podocytes. The Ab EC1 specifically detected endothelial cells. Glomerular endothelium cultured under medium perifusion expressed these typical Ag and thus could be unequivocally discriminated. Furthermore, by means of the proliferation marker Ki-67, it could be demonstrated that glomerulus-like structures developed under culture by proliferation of visceral and parietal cells of Bowman's capsule.

CONCLUSIONS

A culture model is presented that allows the maintenance of developing podocytes within the organ-specific tissue environment and under permanent medium perifusion.

Interrelationship of renal vascular development and nephrogenesis

Within the cortex region of the neonatal rabbit kidney the developing microvasculature was investigated by means of two endothelium-detecting antibodies (EnPo 1 and EC1). Rows of antibody-labelled cells were found within tissue regions that had previously been described as avascular. We conclude that these vessel-like structures detected by EnPo 1 and EC1 are capillary precursors without lumina. Furthermore, beneath the fibrous capsule within the morphologically homogeneous mesenchyme two cell populations can be discriminated by use of differential antigen expression. The EnPo 1 antigen, which is abundant on endothelial cells and podocytes at different developmental stages, was detected on a subpopulation of mesenchymal cells. These cells were exclusively detected surrounding the tip of the collecting duct ampulla. Due to the unique specificity of EC1 and EnPo 1 the process of microvascular development can be readily followed on serial optical sections gained by laser scan microscopy. (1) Adjacent to EnPo 1-positive mesenchymal cell islets vessel-like structures are found that are in contact with the differentiated vasculature. (2) The renal vesicle is enclosed by a network of vessel-like structures establishing contact with differentiated vessels. (3) No guidance of invading capillary sprouts toward the developing glomerulus and nephron is required, since vascular elements already accompany the earliest detectable nephron stage.

Aldosterone modulates PNA binding cell isoforms within renal collecting duct epithelium

To investigate the differentiation of the ampullary collecting duct cells into adult principal and intercalated cells, the embryonic cortex of newborn New Zealand rabbit kidney was isolated and brought in culture. With this culture technique the ampullary cells formed a polarized collecting duct epithelium which was kept under permanent exchange of medium and in the presence of aldosterone, arginine vasopressin and/or insulin. After 14 days of perfusion culture the epithelia showed light and dark cells resembling the principal and intercalated cells of the adult collecting duct. The differentiation from embryonic into adult collecting duct cells was controlled by applying the monoclonal antibody CD 7. Independent of the hormonal treatment all of the epithelial cells matured in culture and expressed the CD 7 antigen. This corresponded with the situation found within the adult kidney, where the CD 7 antigen was localized in all principal and intercalated (IC) cells, whereas the embryonic ampullary epithelium in the neonatal kidney remained negative. A differentiation feature of the beta-type intercalated cell was investigated by labeling the cultured epithelia with peanut agglutinin (PNA). In contrast to the CD 7 antigen the development of PNA binding was highly dependent of time and individual hormone administration. While in control epithelia only 8% of PNA positive cells were found, aldosterone induced epithelia revealed 72% PNA labeled cells. The combination of aldosterone and insulin increased the number of PNA-positive cells to 90%. By scanning electron microscopy it could further be shown that several isoforms of cells were reactive with PNA. Thus, in culture the PNA label is not restricted to the typical beta-type IC cells.

Histochemical markers reveal an unexpected heterogeneous composition of the renal embryonic collecting duct epithelium

The ampullary collecting duct epithelium acts as an inductor in the embryonic and neonatal kidney. It induces the formation of all nephron generations and thus determines the whole architecture of the kidney. As the organ matures, the collecting duct epithelium itself transdifferentiates. The ampullary inductor epithelium, which appears homogeneous as revealed by light microscopy, develops into the well-known heterogeneous epithelium of the mature collecting duct consisting of light principal and dark intercalated cells. Up to now the mechanisms initiating and regulating this transdifferentiation step are unknown. Only very few data are available concerning functional characteristics of the ampullary epithelial cells of neonatal rabbit kidney. Therefore, a characterization of the collecting duct ampullary cells was carried out by means of immunohistological techniques using a set of different monoclonal antibodies and the lectin peanut agglutinin. All epithelial cells within the ampullary tip and neck were positive for cytokeratin 19, an intermediate filament protein. On the other hand, the monoclonal antibody CD 7 revealed a clear cut boundary between the ampullary neck and the ampullary tip region. Furthermore, after incubation with the monoclonal antibody BO-7 specifically reacting with intercalated cells of the mature collecting duct, both labeled and unlabeled cells were observed within the whole ampullary epithelium. These results were confirmed by scanning electron microscopical investigations which revealed two distinct epithelial cell populations. Thus, an unexpected heterogeneity of the ampullary epithelium could be demonstrated.

Characterization of an endothelial protein in the developing rabbit kidney

A new protein (EnPo 1 antigen) abundant on endothelial cells and glomerular podocytes has been characterized by means of the mouse monoclonal antibody EnPo 1. Following electrophoretical separation of rabbit kidney homogenates EnPo 1 recognized a protein with a molecular weight of 110 kDa and an isoelectric point of 5.9 in Western blots. Using immunohistological techniques, the EnPo 1 antigen has been localized in high concentrations on glomerular podocytes of different developmental stages. Furthermore, the EnPo 1 antigen was expressed on endothelial cells of all adult rabbit organs tested so far. Detailed analysis of neonatal rabbit kidney revealed the abundance of EnPo 1 antigen on both differentiated vessels as well as on immature endothelial cells and endothelium of the microvasculature. Thus, for the first time a marker for in situ investigations of angiogenic processes within the mammalian kidney is available. Analysis of kidney cryosections by confocal laser scan microscopy revealed a direct connection between mature and differentiating vessels in the outer kidney cortex. Furthermore, two differentially organized cell populations discriminated by their EnPo 1 binding pattern were localized in the embryonic renal cortex. Morphologically, these cells were not distinguishable from other mesenchymal cells.