Bioresponsive dextrin-rhEGF conjugates: in vitro evaluation in models relevant to its proposed use as a treatment for chronic wounds.
We recently developed a bioresponsive dextrin-recombinant human epidermal growth factor (rhEGF) conjugate as a polymer therapeutic with potential for use in the promotion of tissue repair. The aim of these studies was to use patient-derived wound fluid and fibroblasts to evaluate its potential for further development as a treatment for chronic wounds, such as venous leg ulceration, a growing clinical challenge in the aging population. First, the levels of EGF (ELISA assay), alpha-amylase and elastase (enzyme assays) were measured in patient-derived acute and chronic wound fluid. EGF was detected in acute, but not in chronic wound fluid. alpha-Amylase concentrations were higher in acute (188 IU/L), compared to chronic wound fluid (52 IU/L), but both were in the range of human serum levels. Although elastase was present in chronic wound fluid (2.1 +/- 1.2 RFU/min), none was detected in acute wound fluid. Dextrin-rhEGF incubation in chronic wound fluid led to endogenous alpha-amylase-mediated release of rhEGF (ELISA) that was maximal at 48 h. When the migration of HaCaT keratinocytes and of human fibroblasts (isolated from patient-matched, normal skin and chronic dermal wounds) was studied in vitro using the scratch wound assay, enhanced cell migration was observed in response to both free rhEGF and alpha-amylase-activated dextrin-rhEGF conjugate compared to controls. In addition, fibroblasts displayed increased proliferation (normal dermal fibroblasts approximately 160%; chronic wound fibroblasts approximately 140%) following incubation (72 h) with dextrin-rhEGF that had been exposed to physiological levels of alpha-amylase (93 IU/L). These results suggest further preclinical in vivo evaluation of dextrin-rhEGF is warranted to determine whether conjugate pharmacokinetics and rhEGF liberation into such a complex and aggressive environment can still lead to bioactivity.
Hardwicke
Joseph
J
Wound Biology Group, Cardiff Institute of Tissue Engineering and Repair, Tissue Engineering and Reparative Dentistry, School of Dentistry, Cardiff University, Heath Park, Cardiff CF14 4XY, UK. hardwickej@doctors.org.uk
Moseley
Ryan
R
Stephens
Phil
P
Harding
Keith
K
Duncan
Ruth
R
Thomas
David W
DW
D002460:Cell Line; D002465:Cell Movement / Q000187:drug effects; D049109:Cell Proliferation / Q000187:drug effects; D002478:Cells, Cultured; D003912:Dextrins / Q000737:chemistry*; D004797:Enzyme-Linked Immunosorbent Assay; D004815:Epidermal Growth Factor / Q000737:chemistry / Q000378:metabolism* / Q000494:pharmacology / Q000627:therapeutic use*; D005347:Fibroblasts / Q000166:cytology / Q000187:drug effects; D006801:Humans; D015603:Keratinocytes / Q000166:cytology / Q000187:drug effects; D011994:Recombinant Proteins / Q000737:chemistry / Q000378:metabolism / Q000494:pharmacology / Q000627:therapeutic use; D014945:Wound Healing / Q000187:drug effects*; D000516:alpha-Amylases / Q000378:metabolism*
D003912:Dextrins; D011994:Recombinant Proteins; D004815:Epidermal Growth Factor; D000516:alpha-Amylases