Table 3. Most frequently evaluated therapies across all studies (n = 197).

Therapy	Number of studies evaluating therapy	Direction of effect
Chitosan	6	Four studies [18, 20–22] favoured intervention over control. One study [19] favoured control over intervention. One study [23] showed no difference between intervention and control.
Adipose stromal cells	4	Two studies [25, 27] favoured intervention over control. Two studies [24,26] showed no difference between intervention and control.
Erythropoietin	4	Four studies [28–31] showed no difference between intervention and control
Vascular endothelial growth factor	4	Two studies [32, 35] favoured intervention over control. Two studies [33, 34] showed no difference between intervention and control.
SDF-1	3	Two studies [36, 38] favoured intervention over control. One study [37] showed no difference between intervention and control.
Therapies tested twice	40
Therapies tested once	179