Genaktivierung von bioabbaubaren, implantierbaren Matrices mit einer neuen Klasse nicht-viraler Genvektoren zum Einsatz in der Geweberegeneration von Haut und Knochen

Die aktuellen Herausforderungen der regenerativen Medizin sind geringe Funktionalität und Vaskularisierung, hohe Infektionsraten und inakzeptable Stabilität des zu regenerierenden Gewebes. In dieser Arbeit wurden, durch die Kombination von bioabbaubaren Matrices mit Copolymer-geschützten Genvektoren (COPROGs), Implantate entwickelt, die therapeutische Moleküle freisetzen und somit optimale Vorraussetzungen für die Generation eines voll funktionstüchtigen Gewebes bieten. Es werden unterschiedliche Technologien zur Erzeugung von genaktivierten Matrices beschrieben. Beispielweise ist es gelungen, Implantate zur verbesserten Regeneration von schlecht heilenden Vollhautdefekten durch den Einsatz einer solchen Matrix zu entwickeln, um in Zukunft geringe Vaskularisierungsraten von künstlichem Hautersatz positiv zu beeinflussen. In einem zweiten Ansatz konnte durch eine Oberflächenbeschichtung von bioabbaubaren, jedoch mechanisch stabilen Matrices mit COPROGs, zur Freisetzung von osteoinduktiven Wachstumsfaktoren, ein Implantat entwickelt werden, das die Regeneration von Knochen anstoßen kann. Durch den passgenauen Einsatz in das Wundgebiet bei nicht spontan heilenden Knochendefekten kann indirekt auch die Integrität und mechanische Belastbarkeit der zu regenerierenden Region verbessert werden. Obwohl die in vitro Ergebnisse vielversprechend sind, müssen weitere in vivo Experimente folgen, die die biologische Aktivität in vivo belegen können. Im Weiteren wurde eine duale genaktivierte Matrix durch die Kombination der beiden vorrausgegangen Technologien etabliert, um in komplexen Geweben die Regeneration nach traumatischen Ereignissen möglichst vielseitig, durch die Freisetzung von unterschiedlichen therapeutischen Molekülen von einem Implantat, zu fördern

The use of non-viral gene vectors for bioactive poly-(D,L-lactide) implant surfaces in bone tissue engineering

The application of scaffolds in bone tissue engineering often comes along with side effects such as poor integrity, low regeneration rates of bone tissue with inadequate functionality, and, in case of non-degradable implants, the necessity of a second removal surgery after therapy. In this study, we coated a bioresorbable FDA-approved poly-(ε-caprolactone)-scaffold for bone regeneration with a poly-(D,L-lactide) layer containing copolymer-protected gene vectors to locally provide bone morphogenetic protein-2 (BMP-2). Results show that the presence of such gene vectors did not affect the distribution and attachment of seeded cells on gene-activated surfaces. BMP-2 was released into cell culture supernatants and furthermore detected in homogenised scaffolds. Increased amounts of osteoblastic markers, such as osteocalcin, osteopontin and the activity of alkaline phosphatase, in gene-activated scaffolds in vitro suggest a transdifferentiation of myoblastic C2C12 cells into the osteoblastic phenotype. With this study we present a new technology to bioactivate implant surfaces with non-viral gene vectors. This tool allows the stimulation of tissue regeneration by a local release of therapeutic proteins in vivo

Advanced therapeutic dressings for effective wound healing

Advanced therapeutic dressings that take active part in wound healing to achieve rapid and complete healing of chronic wounds is of current research interest. There is a desire for novel strategies to achieve expeditious wound healing due to the enormous financial burden worldwide. This paper reviews the current state of wound healing and wound management products, with emphasis on the demand for more advanced forms of wound therapy and some of the current challenges and driving forces behind this demand. The paper reviews information mainly from peer reviewed literature and other publicly available sources such as the FDA. A major focus is the treatment of chronic wounds including amputations, diabetic and leg ulcers, pressure sores, surgical and traumatic wounds (e.g. accidents and burns) where patient immunity is low and the risk of infections and complications are high. The main dressings include medicated moist dressings, tissue engineered substitutes, biomaterials based biological dressings, biological and naturally derived dressings, medicated sutures and various combinations of the above classes. Finally, the review briefly discusses possible prospects of advanced wound healing including some of the emerging approaches such as hyperbaric oxygen, negative pressure wound therapy and laser wound healing, in routine clinical care

The use of non-viral gene vectors for bioactive poly-(D,L-lactide) implant surfaces in bone tissue engineering.

The application of scaffolds in bone tissue engineering often comes along with side effects such as poor integrity, low regeneration rates of bone tissue with inadequate functionality, and, in case of non-degradable implants, the necessity of a second removal surgery after therapy. In this study, we coated a bioresorbable FDA-approved poly-(?-caprolactone)-scaffold for bone regeneration with a poly-(D,L-lactide) layer containing copolymer-protected gene vectors to locally provide bone morphogenetic protein-2 (BMP-2). Results show that the presence of such gene vectors did not affect the distribution and attachment of seeded cells on gene-activated surfaces. BMP-2 was released into cell culture supernatants and furthermore detected in homogenised scaffolds. Increased amounts of osteoblastic markers, such as osteocalcin, osteopontin and the activity of alkaline phosphatase, in gene-activated scaffolds in vitro suggest a transdifferentiation of myoblastic C2C12 cells into the osteoblastic phenotype. With this study we present a new technology to bioactivate implant surfaces with non-viral gene vectors. This tool allows the stimulation of tissue regeneration by a local release of therapeutic proteins in vivo

Bioactivation of dermal scaffolds with a non-viral copolymer-protected gene vector.

The use of scaffolds in skin tissue engineering is accompanied with low regeneration rates and high risk of infection. In this study, we activated an FDA-approved collagen scaffold for dermal regeneration by incorporation of copolymer-protected gene vectors (COPROGs) to induce a temporary release of VEGF. In vitro results show that the presence of COPROGs did not affect the distribution, attachment, proliferation and viability of cells in the scaffold. A transient release of VEGF was observed for up to 3 weeks. Moreover a high amount of VEGF was also found in the cells and associated with the scaffold. In a full skin defect model in nude mice, VEGF levels were significantly increased compared to controls in VEGF gene activated scaffolds 14 d after implantation, but not in skin from the wound edge. Results showed an increased amount of non-adherent cells, especially erythrocytes, and von Willebrandt factor (vWF) and a yellow red appearance of gene activated scaffolds in relation to controls. This suggests the presence of leaky vessels. In this work we show that the bioactivation of collagen scaffolds with COPROGs presents a new technology that allows a local release of therapeutic proteins thus enhancing the regenerative potential in vivo

Surgical sutures filled with adipose-derived stem cells promote wound healing.

Delayed wound healing and scar formation are among the most frequent complications after surgical interventions. Although biodegradable surgical sutures present an excellent drug delivery opportunity, their primary function is tissue fixation. Mesenchymal stem cells (MSC) act as trophic mediators and are successful in activating biomaterials. Here biodegradable sutures were filled with adipose-derived mesenchymal stem cells (ASC) to provide a pro-regenerative environment at the injured site. Results showed that after filling, ASCs attach to the suture material, distribute equally throughout the filaments, and remain viable in the suture. Among a broad panel of cytokines, cell-filled sutures constantly release vascular endothelial growth factor to supernatants. Such conditioned media was evaluated in an in vitro wound healing assay and showed a significant decrease in the open wound area compared to controls. After suturing in an ex vivo wound model, cells remained in the suture and maintained their metabolic activity. Furthermore, cell-filled sutures can be cryopreserved without losing their viability. This study presents an innovative approach to equip surgical sutures with pro-regenerative features and allows the treatment and fixation of wounds in one step, therefore representing a promising tool to promote wound healing after injury