Erythropoietin improves functional and histological recovery of traumatized skeletal muscle tissue

Abstract

Apart from its hematopoietic effect, erythropoietin (EPO) is known as pleiotropic cytokine with anti-inflammatory and antiapoptotic properties. Here, we evaluated for the first time the EPO-dependent regeneration capacity in an in vivo rat model of skeletal muscle trauma. A myoblast cell line was used to study the effect of EPO on serum deprivation-induced cell apoptosis in vitro. A crush injury was performed to the left soleus muscle in 80 rats treated with either EPO or saline. Muscle recovery was assessed by analysis of contraction capacities. Intravital microscopy, BrdU/laminin double immunohistochemistry and cleaved caspase-3 immunohistochemistry of muscle tissue on days 1, 7, 14, and 42 posttrauma served for assessment of local microcirculation, tissue integrity, and cell proliferation. Serum deprivation-induced myoblast apoptosis of 23.9 AE 1.5% was reduced by EPO to 17.2 AE 0.8%. Contraction force analysis in the EPO-treated animals revealed significantly improved muscle strength with 10-20% higher values of twitch and tetanic forces over the 42-day observation period. EPO-treated muscle tissue displayed improved functional capillary density as well as reduced leukocytic response and consecutively macromolecular leakage over day 14. Concomitantly, muscle histology showed significantly increased numbers of BrdU-positive satellite cells and interstitial cells as well as slightly lower counts of cleaved caspase-3-positive interstitial cells. EPO results in faster and better regeneration of skeletal muscle tissue after severe trauma and goes along with improved microcirculation. Thus, EPO, a compound established as clinically safe, may represent a promising therapeutic option to optimize the posttraumatic course of muscle tissue healing.

Erythropoietin-induced upregulation of endothelial nitric oxide synthase but not vascular endothelial growth factor prevents musculocutaneous tissue from ischemic damage

“…Several studies have attested EPO anti-apoptotic properties in traumatic, ischemic and toxic injury in a multitude of organs, such as the skeletal muscle, 35 liver 36 and kidney. 11 Our results showed that administration of EPO significantly decreased the number of apoptotic cells when compared with untreated flaps and animals receiving L-Name only.…”

Pulsed Electromagnetic Field Elicits Muscle Recovery via Increase of HSP 70 Expression after Crush Injury of Rat Skeletal Muscle

“…HSP, a stress protein, is synthesized shortly after cells are exposed to stress or a rapid rise in temperature 14) . It functions to minimize cell injury by maintaining proper protein folding with degenerative enzyme proteins and by supporting intracellular homeostasis, including protein transport and synthesis 4,15) . Although HSP 70 is spontaneously expressed under rapidonset pathological conditions, it does not sufficiently protect against cell injury.…”

“…In addition, muscle healing involves the formation of connective scar tissue, not primarily regeneration. The healing process of injured muscle can frequently be hampered by the formation of scar tissue which is characterized by extensive muscle fibrosis and can lead to recurrence of muscle injury 4) . Thus, a therapeutic approach in this phase is important to decrease scar tissue and promote the alignment of muscle fiber for normal contraction.…”

“…Especially, in the case of serious injuries or broad defects, the healing process in impaired muscle tissue is often limited and characterized by extensive muscle fibrosis creating a tendency of muscle injury to recur. For patients with delayed and imperfect posttraumatic healing process of injured muscle, regeneration enhancing strategies are required 3,4) .…”

Applications of <em>In Vivo</em> Functional Testing of the Rat Tibialis Anterior for Evaluating Tissue Engineered Skeletal Muscle Repair

“…More specifically, following extensive cardiotoxin-induced muscle damage (38-67% of muscle fibers 8 ), regeneration is mediated by satellite cells, the resident stem cells that mature to ultimately become functional muscle fibers 4,[9][10][11][12][13] . The end result is increased post-damage functional regeneration of healthy, force-producing muscle tissue [14][15][16] . Although the details are well beyond the scope of this report, the mechanistic basis for muscle regeneration reflects the carefully orchestrated events of numerous cell types from multiple lineages utilizing canonical signaling pathways critical to both tissue development and morphogenesis 5,[17][18][19][20][21] .…”