| 1. |
- Amandusson, Åsa, 1974-
(författare)
-
Estrogen receptor expression in relation to pain modulation and transmission : experimental studies in rats
- 2009
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Estrogens have a remarkably wide range of actions in the mammalian brain. They not only play a pivotal role in reproductive behavior and sexual differentiation, but also contribute to e.g. thermoregulation, feeding, memory, neuronal survival and the perception of somatosensory stimuli. A multitude of studies on both animals and human subjects has demonstrated potential effects of gonadal hormones, such as estrogens, on pain transmission. These effects most likely involve multiple neuroanatomical circuits as well as diverse neurochemical systems and therefore need to be evaluated specifically in relation to the localization and intrinsic characteristics of the neurons engaged. The overall aim of this thesis is to gain specific knowledge of the possible cellular mechanisms by which estrogens may influence the transmission of nociceptive stimuli at the level of the spinal cord. The estrogen receptors, by which estrogens regulate non-genomic as well as genomic mechanisms, are crucial to estrogen signaling in general and essential to the estrogen-induced effects in the brain. In Paper I, we use immunohistochemistry to label neurons containing estrogen receptor-! (ERα) in the medullary and spinal dorsal horn of female rats. Large numbers of ER!-expressing neurons were found in lamina I and lamina II, i.e. in the areas involved in the processing of primary afferent nociceptive information. This distribution in part overlaps that of enkephalin, a potent pain-inhibiting endogenous opioid. The effects of gonadal hormones on pain modulation may, to a great extent, be blocked by the opioid antagonist naloxone, suggesting an involvement of the endogenous opioid system in the prosecution of hormonal pain regulation. By combining immunohistochemical labeling of ERα with in situ hybridization of preproenkephalin mRNA (Paper II), we demonstrate that the majority of enkephalinergic neurons in the superficial laminae of the spinal and medullary dorsal horn express ER!. This co-localization and the fact that the preproenkephalin gene contains a sequence that binds ERs, suggest that estrogens may potentially regulate enkephalin expression in these cells. This is further supported by the findings in Paper III in which we show that a single subcutaneous injection of estradiol induces a significant increase (on average 68%) in preproenkephalin mRNA content in the spinal cord after 4 hours. The expression of the enkephalin gene in the spinal cord is thus sensitive to fluctuating estradiol levels. In Paper IV, a noxious injection of formalin is used to induce activation of a neuronal population involved in nociceptive transmission from the face. By using a dual-labeling immunohistochemistry protocol, we were able to identify ER!-expressing cells within this neuronal population suggesting that nociceptive-responsive neurons in the medullary dorsal horn express ER!. In all, our findings provide morphological as well as biochemical evidence in support for an estrogen-dependent modulation of nociceptive processing at the level of the dorsal horn.
|
|
| 2. |
- Huss, Fredrik R.M. 1971-
(författare)
-
In vitro and in vivo studies of tissue engineering in reconstructive plastic surgery
- 2005
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- To correct, improve, and maintain tissues, and their functions, are common denominators in tissue engineering and reconstructive plastic surgery. This can be achieved by using autolo-gous tissues as in flaps or transplants. However, often autologous tissue is not useable. This is one of the reasons for the increasing interest among plastic surgeons for tissue engineering, and it has led to fruitful cross-fertilizations between the fields. Tissue engineering is defined as an interdisciplinary field that applies the principles of engineering and life sciences for development of biologic substitutes designed to maintain, restore, or improve tissue functions. These methods have already dramatically improved the possibilities to treat a number of medical conditions, and can arbitrarily be divided into two main principles:> Methods where autologous cells are cultured in vitro and transplanted by means of a cell suspension, a graft, or in a 3-D biodegradable matrix as carrier.> Methods where the tissue of interest is stimulated and given the right prerequisites to regenerate the tissue in vivo/situ with the assistance of implantation of specially designed materials, or application of substances that regulate cell functions - guided tissue regeneration.We have shown that human mammary epithelial cells and adipocytes could be isolated from tissue biopsies and that the cells kept their proliferative ability. When co-cultured in a 3-D matrix, patterns of ductal structures of epithelial cells embedded in clusters of adipocytes, mimicking the in vivo architecture of human breast tissue, were seen. This indicated that human autologous breast tissue can be regenerated in vitro.The adipose tissue is also generally used to correct soft tissue defects e.g. by autologous fat transplantation. Alas 30-70% of the transplanted fat is commonly resorbed. Preadipocytes are believed to be hardier and also able to replicate, and hence, are probably more useful for fat transplantation. We showed that by using cell culture techniques, significantly more pre-adipocytes could survive and proliferate in vitro compared to two clinically used techniques of fat graft handling. Theoretically, a biopsy of fat could generate enough preadipocytes to seed a biodegradable matrix that is implanted to correct a defect. The cells in the matrix will replicate at a rate that parallels the vascular development, the matrix subsequently degrades and the cell-matrix complex is replaced by regenerated, vascularized adipose tissue.We further evaluated different biodegradable scaffolds usable for tissue engineering of soft tissues. A macroporous gelatin sphere showed several appealing characteristics. A number of primary human ecto- and mesodermal cells were proven to thrive on the gelatin spheres when cultured in spinner flasks. As the spheres are biodegradable, it follows that the cells can be cultured and expanded on the same substrate that functions as a transplantation vehicle and scaffold for tissue engineering of soft tissues.To evaluate the in vivo behavior of cells and gelatin spheres, an animal study was performed where human fibroblasts and preadipocytes were cultured on the spheres and injected intra-dermally. Cell-seeded spheres were compared with injections of empty spheres and cell suspensions. The pre-seeded spheres showed a near complete regeneration of the soft tissues with neoangiogenesis. Some tissue regeneration was seen also in the ‘naked’ spheres but no effect was shown by cell injections.In a human pilot-study, intradermally injected spheres were compared with hyaluronan. Volume-stability was inferior to hyaluronan but a near complete regeneration of the dermis was proven, indicating that the volume-effect is permanent in contrast to hyaluronan which eventually will be resorbed. Further studies are needed to fully evaluate the effect of the macroporous gelatin spheres, with or without cellular pre-seeding, as a matrix for guided tissue regeneration. However, we believe that the prospect to use these spheres as an injectable, 3D, biodegradable matrix will greatly enhance our possibilities to regenerate tissues through guided tissue regeneration.
|
|
