Wound healing is a complex multicellular process that involves the infiltration of blood cells to remove cellular debris, and the recruitment of endogenous stem cells to replace the damaged tissue. One of the newly identified cellular players in the wound healing process is the blood derived stromal-like cell, which appears to demonstrate stem cell-like properties. A number of evidence demonstrates that stromal-like cells are recruited to the site of injury, where they differentiate into the necessary cell types to repair the damaged tissue (1).
Although stromal-like cells are recruited with the help of various injury-induced factors, one particular factor that is of interest is substance P (SP). Substance P is a pain neurotransmitter in the central nervous system, and is involved in the processing of pain sensation. Intriguingly, a recent report in April 2009 issue of Nature Medicine revealed that SP is also an endogenous injury-induced factor involved in stromal-like cell recruitment and wound healing (1). Furthermore, the study showed that application of SP to an epithelial wound resulted in significantly greater stromal-like cell recruitment and faster healing.
The above study strongly implicates the direct role of SP in mediating wound healing through stromal-like cell recruitment. Since SP is also upregulated following neurotrauma(2), it may be likely that SP could play a role in stromal-like cell recruitment and CNS repair. Perhaps future characterization of SP expression and stromal-like cell behaviour following neurotrauma may provide insights into developing novel therapeutics for spinal cord injury and stroke.
1. Hong et al., 2009. Nature Medicine. 15(4): 425-435.
2. Milligan & Watkins, 2009. Nature Rev Neurosci. 10: 23-36.