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Live kidney donors are healthy volunteers who are exposed to major surgical procedure and physical harms with no direct therapeutic benefits. Efforts to minimize their risks and morbidity are therefore of utmost importance. The current thesis describes studies on donor evaluation, surgical procedure and postoperative management of live kidney donors. The overall purpose is to evaluate and possibly improve routines and treatments in order to reduce risks and the overall morbidity of live kidney donors. In Study I, we evaluated the assessment of kidney function during donor evaluation and found that the accuracy of iohexol glomerular filtration rate (GFR) is compromised by large variations in repeated measurements in presumably healthy donors. We proposed that there is a need for improvement of GFR measurements and that the assessment of predonation kidney function should be more comprehensive, involving GFR, laboratory investigations, functional and morphological examinations and sound clinical judgment. In Study II, we addressed the risk of perioperative venous thromboembolism (VTE) and concluded that expanding the standard screening protocol for VTE to include perioperative venous duplex can potentially decrease the VTE-related morbidity. In studies III and IV, we investigated the impact of hand-assisted retroperitoneoscopic (HARS) nephrectomy on donor safety and perioperative morbidity. The HARS nephrectomy uses the hand-assisted approach, which enables immediate manual compression for hemostasis in case of sudden and severe bleeding. Additionally, the pure retroperitoneal access further increases the safety margin of laparoscopic donor nephrectomy by 1) minimizing the risk of intestinal injury, and 2) exposure of the retroperitoneal nerves, making HARS suitable for continuous infusion of local anesthetics (CILA). CILA effectively reduces the need for opioid consumption and has the potential to totally obviate opiate analgesics postoperatively. Consequently, CILA in combination with HARS reduces morphine-related morbidity and promotes postoperative recovery. In accordance with these data, we recommend improvement and modification of the donor evaluation process as well as a broad introduction of HARS nephrectomy in combination with CILA to increase the safety margin for live kidney donors.

The extracellular matrix is (ECM) is a network of large, structural proteins and polysaccharides, important for cellular behavior, tissue development and maintenance. Present thesis describes work exploring ECM as scaffolds for tissue engineering by manipulating cells cultured in vitro or by influencing ECM expression in vivo. By culturing cells on polymer meshes under dynamic culture conditions, deposition of a complex ECM could be achieved, but with low yields. Since the major part of synthesized ECM diffused into the medium the rate limiting step of deposition was investigated. This quantitative analysis showed that the real rate limiting factor is the low proportion of new proteins which are deposited as functional ECM. It is suggested that cells are pre-embedded in for example collagen gels to increase the steric retention and hence functional deposition. The possibility to induce endogenous ECM formation and tissue regeneration by implantation of growth factors in a carrier material was investigated. Bone morphogenetic protein-2 (BMP-2) is a growth factor known to be involved in growth and differentiation of bone and cartilage tissue. The BMP-2 processing and secretion was examined in two cell systems representing endochondral (chondrocytes) and intramembranous (mesenchymal stem cells) bone formation. It was discovered that chondrocytes are more efficient in producing BMP-2 compared to MSC. The role of the antagonist noggin was also investigated and was found to affect the stability of BMP-2 and modulate its effect. Finally, an injectable gel of the ECM component hyaluronan has been evaluated as delivery vehicle in cartilage regeneration. The hyaluronan hydrogel system showed promising results as a versatile biomaterial for cartilage regeneration, could easily be placed intraarticulary and can be used for both cell based and cell free therapies.

Islet transplantation has found its niche in diabetes treatment. It has contributed to a better quality of life and better glycemic control of patients with diabetes suffering from severe hypoglycemia that are not eligible for vascularized pancreas transplantation. Islet isolation is a technically challenging procedure. The different studies within this doctoral thesis aim to improve and standardize different steps in the isolation procedure. They are in particular looking to improve human pancreas preservation during cold storage, to optimize islet release from the exocrine tissue and to assess whether the isolated islet yield can be predicted from a biopsy. We found that pancreas preservation with pre-oxygenated perfluorodecalin (two-layer method) did not improve the ischemic tolerance of the human pancreas as compared to cold storage with the University of Wisconsin (UW) solution. Furthermore, in pancreas with long cold ischemia time (CIT) (>10 hours), Histidine-Tryptophan-Ketoglutarate (HTK) had a limited preservation capacity as compared with the UW solution with respect to isolation outcome. We also found that during enzymatic pancreas digestion, Vitacyte HA was able to provide a similar islet yield and quality as Serva NB1 with less collagenase activity and shorter digestion time. We further describe the first experience with a new GMP manufactured enzyme called Liberase MTF-S for successful human islet isolation. Finally, we found that the isolated islet yield could not be predicted from a biopsy taken from the head of the pancreas concerning solely morphological parameters of the islets tissue. The improvement of pancreas preservation will allow for marginal organs with prolonged cold ischemia time to expand the donor pool. Better knowledge of how the pancreatic extracellular matrix is digested by collagenase will lead to a fast and predictable islet release from the exocrine tissue. By standardizing the isolation procedure and improving organ selection we will increase the success rate in human islet isolation, thereby making islet transplantation available for more patients.