Strategies to promote tendon-bone healing after anterior cruciate ligament reconstruction: Present and future

At present, anterior cruciate ligament (ACL) reconstruction still has a high failure rate. Tendon graft and bone tunnel surface angiogenesis and bony ingrowth are the main physiological processes of tendon-bone healing, and also the main reasons for the postoperative efficacy of ACL reconstruction. Poor tendon-bone healing has been also identified as one of the main causes of unsatisfactory treatment outcomes. The physiological process of tendon-bone healing is complicated because the tendon-bone junction requires the organic fusion of the tendon graft with the bone tissue. The failure of the operation is often caused by tendon dislocation or scar healing. Therefore, it is important to study the possible risk factors for tendon-bone healing and strategies to promote it. This review comprehensively analyzed the risk factors contributing to tendon-bone healing failure after ACL reconstruction. Additionally, we discuss the current strategies used to promote tendon-bone healing following ACL reconstruction.

Potential influences of expression levels of MFGE8 and HMGB1 on the intestinal mucosal barrier function and inflammatory response after blunt abdominal injury in rats

Purpose:

To explore the influence of milk fat globule-EGF factor 8 protein (MFGE8) on blunt abdominal injury in Sprague Dawley (SD) rats through the RhoA/ROCK signaling pathway.

Methods:

The blunt abdominal injury model was generated in SD rats. A total of 44 rats was randomly assigned into three groups. Rat blunt abdominal injury was assessed by the abbreviated injury scale (AIS). The rats were sacrificed for observing the morphology of the abdominal cavity and intestines. Hematoxylin and eosin staining was performed to visualize the pathological changes of rat intestines. Positive expressions of MFGE8 and high mobility group box 1 (HMGB1) in rat intestines were examined by immunohistochemical staining. Protein levels were determined by Western blot. Serum levels of tumor necrosis factor α (TNF-α), IL-1β, IL-6 and malondialdehyde (MDA) were measured by enzyme linked immunosorbent assay (ELISA).

Results:

Blunt abdominal injury resulted in inflammatory response of intestinal tissues, increased serum levels of TNF-α, IL-1β, IL-6 and MDA, upregulation of HMGB1, RhoA and ROCK2, and downregulation of MFGE8 in rats, which were significantly alleviated by intervention of rhMFGE8.

Conclusions:

MFGE8 protects the intestinal mucosal barrier function after blunt abdominal injury in rats by downregulating HMGB1. Moreover, it alleviates inflammatory response and oxidative stress caused by blunt abdominal injury in rats through downregulating RhoA and ROCK.

Milk fat globule EGF factor 8 restores mitochondrial function via integrin-medicated activation of the FAK-STAT3 signaling pathway in acute pancreatitis

Acute pancreatitis (AP) remains a significant clinical challenge. Mitochondrial dysfunction contributes significantly to the pathogenesis of AP. Milk fat globule EGF factor 8 (MFG-E8) is an opsonizing protein, which has many biological functions via binding to αvβ3/5 integrins. Ligand-dependent integrin-FAK activation of STAT3 was reported to be of great importance for maintaining a normal mitochondrial function. However, MFG-E8's role in AP has not been evaluated.

METHODS

Blood samples were acquired from 69 healthy controls and 134 AP patients. Serum MFG-E8 levels were measured by ELISA. The relationship between serum concentrations of MFG-E8 and disease severity were analyzed. The role of MFG-E8 was evaluated in experimental models of AP.

RESULTS

Serum concentrations of MFG-E8 were lower in AP patients than healthy controls. And serum MFG-E8 concentrations were negatively correlated with disease severity in AP patients. In mice, MFG-E8 administration decreased L-arginine-induced pancreatic injury and mortality. MFG-E8's protective effects in experimental AP were associated with improvement in mitochondrial function and reduction in oxidative stress. MFG-E8 knockout mice suffered more severe pancreatic injury and greater mitochondrial damage after l-arginine administration. Mechanistically, MFG-E8 activated the FAK-STAT3 pathway in AP mice. Cilengitide, a specific αvβ3/5 integrin inhibitor, abolished MFG-E8's beneficial effects in AP. PF00562271, a specific FAK inhibitor, blocked MFG-E8-induced STAT3 phosphorylation. APTSTAT3-9R, a specific STAT3 antagonist, also eliminated MFG-E8's beneficial effects under such a condition.

CONCLUSIONS

MFG-E8 acts as an endogenous protective mediator in the pathogenesis of AP. MFG-E8 administration protects against AP possibly by restoring mitochondrial function via activation of the integrin-FAK-STAT3 signaling pathway. Targeting the action of MFG-E8 may present a potential therapeutic option for AP.