Activated omentum becomes rich in factors that promote healing and tissue regeneration

Abstract

In order to study the mechanism by which an omental pedicle promotes healing when applied to an injured site, we injected a foreign body into the abdominal cavity to activate the omentum. One week after the injection, we isolated the omentum and measured blood vessel density, blood content, growth and angiogenesis factors (VEGF and others), chemotactic factors (SDF-1 alpha), and progenitor cells (CXCR-4, WT-1). We found that the native omentum, which consisted mostly of adipose tissue, expanded the mass of its non-adipose part (milky spots) 15- to 20-fold. VEGF and other growth factors increased by two- to four-fold, blood vessel density by three-fold, and blood content by two-fold. The activated omentum also showed increases in SDF-1 alpha, CXCR-4, and WT-1 cells (factors and cells positively associated with tissue regeneration). Thus, we propose that an omentum activated by a foreign body (or by injury) greatly expands its milky-spot tissue and becomes rich in growth factors and progenitor cells that facilitate the healing and regeneration of injured tissue.

Omentum facilitates liver regeneration

“…These findings suggest that the omentum plays an important role in bringing about growth and regeneration of the injured liver. The amount of liver growth induced by the omentum was proportional to the degree of omental activation, consistent with our previous observations that the concentration of growth factors and the number of progenitor cells in the omentum increase with increased activation [7,8] .…”

“…In previous studies we investigated this process and found that these properties can be enhanced by physically expanding the omentum with foreign particles. Under such conditions, the expanded omentum becomes rich in growth and angiogenic factors, and has abundant progenitor cells [7,8] . In a separate study we used this approach to generate new β-cells from the diabetic pancreas [11] .…”

“…These proper ties have found clinical application where the omentum is surgically brought into contact with injured tissues such as ischemic heart, fractured bones, or injured spinal cord [3][4][5][6] . We have recently shown that introducing a foreign body into the peritoneal cavity further enhanced the healing power of the omentum by causing it to expand, surround the foreign body, and transform itself from mostly fatty tissue to tissue abundant in progenitor cells and rich in growth and angiogenic factors (activated omentum) [7,8] . Because liver regeneration can be brought about by resident stem cells (oval cells) even in the absence of hepatocyte multiplication [9,10] , we attempted to use the activated omentum to facilitate liver regeneration.…”

Reduction of epidural fibrosis after laminectomy in rabbits by omental free graft

“…We noticed that the level of foreign body reaction was significantly lower with the application of the free omental graft. We assume it was due to the known omental antiinflammatory properties (Alagumuthu et al 2006), as well as its positive effect on regeneration and healing (Litbarg et al 2007).…”

“…The potent lymphatic system of the omentum can absorb large amounts of oedema fluids and remove metabolic wastes and toxic substances (Alagumuthu et al 2006). Omentum is also rich in growth factors and stem cells that promote healing and tissue regeneration (Litbarg et al 2007). Therefore, our hypothesis was that free omental graft would be a suitable interposition membrane which could reduce postoperative epidural fibrosis and consequent scar adhesion after laminectomy procedures.…”