Biomedical subjects

Gunnar Kratz

Publications and source records attributed to Gunnar Kratz.

10 recordsLinked to original sources

PubMed2006

Estradiol increases VEGF in human breast studied by whole-tissue culture.

Sex steroid exposure constitutes a risk factor for breast cancer, but little is known about the effects of sex steroids on the normal breast, largely because of the lack of convenient models. We have developed a method of culturing normal breast tissue ex vivo. We have applied this method to investigate the effects of estradiol and progesterone on the key angiogenic mediator, vascular endothelial growth factor (VEGF), in the breast. Whole breast tissue was obtained from routine reduction mammoplasty. Tissue biopsies were cultured in vitro for 1-3 weeks, and the expression of luminal cytokeratin 18 was determined by immunohistochemistry. As an application, tissue biopsies were treated in vitro for 1 week with or without estradiol or estradiol and progesterone. Estrogen receptor, progesterone receptor, and Ki-67 were analyzed, and VEGF levels were examined by quantitative immunoassay and immunohistochemistry. Whole breast tissue was cultured ex vivo for 1 week with preserved morphology. Increased detachment of the luminal epithelium was observed after 2 weeks. Estradiol increased extracellular levels of VEGF in normal breast tissue biopsy medium. The addition of progesterone had neither stimulatory nor inhibitory effects on secreted VEGF. The method of whole breast tissue culturing thus provide a means by which to explore the biology of normal breast tissue. Our results suggest that estradiol exerts pro-angiogenic effects in normal breast by increasing levels of biologically active VEGF.

Biomarkers↗

PubMed2005

Expression and growth dependency of the insulin-like growth factor I receptor in craniopharyngioma cells: a novel therapeutic approach.

Craniopharyngioma is a rare benign intracranial epithelial tumor that, however, often recurs and sometimes kills the affected patients, one-third of which are children. In many cases, the patients acquire growth hormone deficiency and postoperatively need substitution. Generally, growth hormone promotes local release of insulin-like growth factor I (IGF-I), which in turn activates the IGF-I receptor (IGF-IR) if present. Together, these circumstances raise the question whether IGF-IR may be involved in craniopharyngioma growth. To address this issue, we analyzed phenotypically well-characterized primary low-passage craniopharyngioma cell lines from nine different patients for IGF-IR expression and IGF-I dependency. Two of the cell lines showed no/very low expression of the receptor and was independent on IGF-I, whereas five cell lines exhibited a strong expression and was clearly contingent on IGF-I. The two remaining cell lines had low receptor expression and IGF-I dependency. Upon treatment with an IGF-IR inhibitor, cells with high IGF-IR expression responded promptly with decreased Akt phosphorylation followed by growth arrest. These responses were not seen in cells with no/very low receptor expression. Growth of cell lines with low IGF-IR expression was only slightly affected by IGF-IR inhibition. Taken together, our data suggest that IGF-IR may be involved in the growth of a subset of craniopharyngiomas and points to the possibility of the involvement of IGF-IR inhibitors as a treatment modality to obtain complete tumor-free conditions before growth hormone substitution.

Adolescent↗

PubMed2005

Long-term culture of human urothelial cells--a qualitative analysis.

Today, in vitro culturing of autologous cells is an established method in the field of tissue reconstruction. It can be applied to urothelial cells and could have many clinical implications in urological reconstructive surgery. This development calls for quality controls concerning cells used for clinical treatment when cells are autotransplanted back to the patient. We have studied cultured cells in order to detect whether genetic or morphologic changes occur. Urothelial cells isolated from bladder lavage were cultured according to different protocols based on the presence or absence of feeder cells. Genetic studies were performed by means of karyotyping with standard G-banding and interphase fluorescent in situ hybridization (FISH) analyses. The morphology of these epithelial cells was judged as well as immunostaining for epithelial cell markers. In addition, to minimize the risk of feeder cell contamination, proliferation studies were performed on cultures including feeder cells that had been pretreated with different doses of mitomycin or radiation. In initial studies, when using feeder cells in each passage according to standard protocols, urothelial cells proliferated unfavourably after the fourth passage with increasing numbers of mouse cells as well as urothelial tetraploid cells. We could also show that urothelial cells from bladder lavage need feeder cells in order to establish primary cultures. Further propagation up to 14 passages was performed without feeder cells and the urothelial cells retained normal karyotypes. We also found that mitomycin treatment had its main effect on feeder cells during the first 2 h. When feeder cells were irradiated, 20 Gy was effective and no feeder cell contamination was seen. In conclusion, we found that a high standard of quality in urothelial cell culturing can be achieved with a careful culturing technique.

Animals↗

PubMed2004

[Lightning injuries--a mixture of electrical, thermal and multiple trauma].

There are several misconceptions even among hospital personnel regarding damages and injuries caused by lightning. Few health care providers have experience from lightning injuries as they are rare and different (DC) from the more common high-voltage (AC) injuries. Furthermore, fatalities are uncommon. Burns do occur but are usually minor. Most lightning injuries occur in the summer season during outdoor leisure activities and in the vicinity of a tree or other large structures. In Sweden, on average, approximately seventeen persons per year are hospitalised and 0.2-0.8 persons per million inhabitants and year die due to lightning injuries. The primary treatment follows the general guidelines for other trauma, electrical, and burn injuries, i.e. as is described in the standardised ATLS, ABLS, or A-HLR programmes. However, there are some minor points that are different and may be stressed for a favourable outcome. In this paper these are addressed together with the epidemiology, effects and treatment of lightning injuries that are specific for Sweden. Unfortunately, little is known, apart from what is described in smaller case series, of the long time sequelae experienced by this patient population and further research is therefore particularly warranted in this respect.

Humans↗

PubMed2003

The cathelicidin anti-microbial peptide LL-37 is involved in re-epithelialization of human skin wounds and is lacking in chronic ulcer epithelium.

The human cathelicidin anti-microbial protein, hCAP18 is a component of the innate immune system and has broad anti-microbial activity conferred by its C-terminal fragment LL-37. hCAP18 is constitutively produced in leukocytes and is induced in barrier organs upon inflammation and infection. We demonstrate here a novel role for this peptide in re-epithelialization of skin wounds. We show that high levels of hCAP18 are produced in skin in vivo upon wounding. The highest hCAP18 levels are attained at 48 h post-injury, declining to pre-injury levels upon wound closure. hCAP18 is detected in the inflammatory infiltrate and in the epithelium migrating over the wound bed. In chronic ulcers, however, hCAP18 levels are low and immunoreactivity for hCAP18/LL-37 is absent in ulcer edge epithelium. Using a noninflammatory ex vivo wound healing model, composed of organ-cultured human skin, we show that hCAP18 is strongly expressed in healing skin epithelium, and that treatment with antibodies raised and affinity purified against LL-37, inhibits re-epithelialization in a concentration-dependent manner. Immunoreactivity for the proliferation marker Ki67 is absent in the epithelium of such inhibited wounds, suggesting that LL-37 may play a part in epithelial cell proliferation. Thus, we suggest that, in addition to being an anti-microbial peptide, LL-37 also plays a part in wound closure and that its reduction in chronic wounds impairs re-epithelialization and may contribute to their failure to heal.

Antibodies↗

PubMed2003

Isolation and in vitro cultivation of human urothelial cells from bladder washings of adult patients and children.

To acquire urothelial cells for in vitro engineering of urothelium, biopsy specimens were taken from the urological tract. In clinical practice the number of cells harvested by biopsy are limited and the procedure requires general anaesthesia in children. The purpose of this study was to find out if bladder washings from adult patients as well as children contained enough proliferative and colony-forming uroepithelial cells to regenerate urethral mucosa in vitro, and if the cells could be stored by freezing. Bladder washings from nine children and eight adult patients were collected from patients who were having procedures that required an indwelling catheter. All cultures grew colonies of cells with a morphological appearance typical for epithelial cell growth. The cultures could be expanded to confluent, stratified sheets, and cells that stained for pancytokeratin, indicating an epithelial origin. Cells stored in -150 degrees C could be cultured and expanded in vitro. No differences were seen between cells from adults and children. Bladder washing is a non-invasive way to obtain many autologous urothelial cells. The method is reproducible and well tolerated by children. The possibility of culturing cells obtained in this way into stratified grafts provides a unique way of reconstructing the urogenital tract by "tissue engineering".

Adult↗

PubMed2003

Tissue engineering by cocultivating human elastic chondrocytes and keratinocytes.

To date, there is no optimal way to reconstruct an external ear in cases of microtia or after trauma or burns damaging the external ear. However, success in the area of tissue engineering has indicated that autologous elastic cartilage produced in vitro might be of great importance in the future treatment of these patients. In the present study we have engineered human, elastic cartilage in vitro by culturing chondrocytes in fibrin glue. Furthermore, the engineered elastic cartilage was seeded with human keratinocytes to investigate the possibility of combining these two tissues into one integrated structure. Histological analysis and immunohistochemistry were done every second week for 10 weeks. The elastic chondrocytes were shown to grow well in the matrix and proliferated in a dense pattern. After 10 weeks a matrix containing elastin was shown by staining with orcein, indicating that an elastic cartilage had been formed. The seeded keratinocytes adhered to the cartilage, proliferated, and formed a stratified epidermal layer, which was shown by routine histological staining and immunohistochemistry. This study shows that human elastic chondrocytes can be cultured in fibrin glue and that human keratinocytes can be cocultured with this engineered cartilage, which might be of great importance in future reconstruction of ears.

Biomarkers↗

PubMed2003

Plastic surgery.

Explore the source record for details and available documents.

Humans↗

PubMed2002

Adipose tissue processed for lipoinjection shows increased cellular survival in vitro when tissue engineering principles are applied.

Correcting soft tissue defects by autologous fat grafting is a routine procedure in plastic surgery. Its efficacy and safety has been discussed extensively and several techniques of lipoinjection have been developed. However, one is bound to overcorrect by 30%-70% or need to repeat the procedure because of resorption of the transplant. The reasons are that many of the transplanted cells are already differentiated, and also that there is no nutritional support to the inner cell layers when they are transplanted as fragments. By culturing autologous adipocytes one can ensure that only non-differentiated, but committed, preadipocytes are transplanted and the procedure can be done in a way that ensures optimal nutritional support for the cells. In the present study we have compared our cell culture technique with two common clinical ways of processing liposuction material and found that (pre)adipocytes survive and proliferate significantly better in cell culture.

Abdomen↗

PubMedDate not supplied

Engineering of multilayered urinary tissue in vitro.

Regeneration of the urinary conduit, using engineered autologous material, could have many clinical implications. The urinary system is composed of a three-layered wall consisting of different cell types. In this study we investigated the possibility to coculture these components in vitro into a continuous sheet for total autologous regeneration. To address this issue, human urothelial cells, fibroblasts, and smooth muscle cells were isolated separately and expanded in vitro. Cells were then cocultured by seeding them in layers in a "sandwich model." After coculturing the material was investigated histologically and with immunoassays. The different cells could be cocultured after being isolated and expanded separately in vitro. The cells formed a continuous sheet that could be enzymatically detached and that sustained mechanical handling. The morphology of different cell layers and the reaction to immunostaining indicated their preserved individual phenotype. In conclusion, we showed that human urothelial cells, fibroblasts, and smooth muscle cells can be expanded in vitro and cocultured to form a continuous cellular sheet consisting of three distinct layers of different types of cells. This could provide the surgeon with autologous tissue for urogenital reconstructive purposes.

Actins↗