Accelerated wound healing by on-site production and delivery of CXCL12

Sammanfattning: Non-healing wounds is a growing medical problem, often associated with pathological conditions such as diabetes and peripheral ischemia. A non-healing wound entails a large amount of suffering for the patient, and demands extensive health care resources. In this thesis, a new drug treatment paradigm for wound healing was developed by transforming Limosilactobacillus reuteri R2LC with a plasmid encoding CXCL12 (LB_CXCL12). The drug candidate was tested for safety and biological effects following topical administration to full thickness wounds in both mice and minipigs. In parallel, different techniques, including 2D and 3D measurements, planimetry, and ultrasound, for assessing wound healing were developed and evaluated.  Murine wounds treated with LB_CXCL12 demonstrated increased proliferation of dermal cells, and an increased density of macrophages of which a larger fraction expressed TGF-β. If macrophages were depleted prior to wounding, the accelerated effect on healing was abolished demonstrating a macrophage-dependent mechanism of action. Importantly, the LB_CXCL12 treatment also accelerated wound healing in mice with impaired healing as a result of hyperglycemia or peripheral ischemia, conditions that in humans are associated with development of non-healing wounds. Wounds in minipigs treated with the freeze-dried formulation of LB_CXCL12, upon resuscitation referred to as ILP100, showed accelerated healing both by increased granulation tissue formation and accelerated re-epithelialization. The treatment with ILP100 was well tolerated with no treatment-related deviations in haematology, urinalysis, and histopathology. Further, we found improved detection of thin layers if newly formed epithelial using planimetry and ultrasound compared to 2D photographs, whereas 3D scans accounting for surface curvatures yielded larger wound areas than 2D photographs of the same wounds. Development of topical treatments for non-healing wounds are limited by the proteolytic environment of the wound that cause degradation of applied molecules. Our developed technology, a new-in-class candidate, overcomes this by continuous on-site delivery and increased bioavailability of CXCL12, resulting in prolonged instruction of local immune cells to stimulate wound healing.