TABLE 3.
Platelet-rich plasma preparation protocols of included alopecia areata studies.
| References | No. of session | Interval | Max F/U | Route of application | Protocol/rpm or G—centrifuged time | Activator | Blood volume/PRP volume |
| Randomized control studies | |||||||
| Trink et al. (33) | 3 | 4 weeks | 52 weeks | Intralesional injected | Single spin method ● 70 G–8 min |
Calcium gluconate | 36 ml/NR |
| El Taieb et al. (34) | 3 | 4 weeks | 12 weeks | Intralesional injection | Single spin method ● 3000 rpm–10 min |
Calcium gluconate | 10/4 ml |
| Nagaratna et al. (35) | 4 | 3 weeks | 36 weeks | Microneedling using a dermaroller then intermittent application of PRP | Double spin method ● 3000 rpm–15 min ● 2000 rpm–10 min |
NR | 8/5 ml |
| Khademi et al. (36) | 4 | 4 weeks | 16 weeks | Intralesional injection (0.1 ml/1.5–2 cm2) | Single spin method ● 3500 rpm–5 min |
Calcium gluconate ● Calcium bicarbonate (0.1 ml per PRP 4 ml) |
8/4 ml |
| Albalat and Ebrahim (37) | 3–5 | 2 weeks | 24 weeks | Intralesional injection (0.1 ml/cm2) | Double spin method ● 150 G–10 min ● 1500–2000 G–10 min |
CaCl2 (0.1 ml of CaCl2 per 0.9 ml of PRP) | 15/3 ml |
| Ragab et al. (38) | 3 | 4 weeks | 24 weeks | Group A: Intralesional PRP injection ● Group B: FCL followed by topical PRP ● Group C: microneedling by dermalroller (1.5 mm needles) followed by topical PRP |
Double spin method ● 1000 rpm–15 min ● 4000 rpm–10 min |
3% CaCl2 (0.1 ml for each 1 ml of PRP) | 10 ml/NR |
| Kapoor et al. (39) | 4 | 3 weeks | 24 weeks | Intralesional injection (0.1 ml/cm2) | Single spin method/2000 rpm–3 min | NR | 20 ml/NR |
| Hegde et al. (40) | 3 | 4 weeks | 20 weeks | Intralesional injection (0.1 ml/cm2) | Double spin method ● 1400 rpm–10 min ● 2800 rpm–10 min |
NR | 8.5 ml/NR |
| Balakrishnan et al. (41) | 3 | 4 weeks | 12 weeks | Intralesional injected 45° angle (0.1 ml/cm2) | Double spin method ● 1500 rpm–15 min ● 2500 rpm–10 min |
CaCl2 (add CaCl2 0.1 ml per 0.9 ml of PRP) | 15/3 ml |
| Gupta et al. (42) | 3 | 4 weeks | 20 weeks | Intralesional injection (0.1 ml/cm2) | Manual double spin method ● 160 G–10 min ● 400 G–10 min |
Calcium gluconate (1:9 ratio) | 40/4–5 ml |
| Tawfik et al. (43) | 6 | 1 week | 18 weeks | Intralesional injection | Single spin method/3500 rpm–10 min | NR | 10/5 ml |
| Non-randomized studies | |||||||
| Singh (44) | 6 | 4 weeks | 52 weeks | Intralesional injection | NR | NR | 25 ml/NR |
| Khan et al. (45) | 3 | 4 weeks | 36 weeks | Intralesional injection (0.1 ml/cm2 at a site 1 cm apart) | Takikawa’s manual double spin method with slight modification ● 2000 rpm–10 min ● 4000 rpm–10 min |
10% CaCl2 (0.3 ml for 1 ml of PRP) | 15 ml/NR |
| Fayed et al. (46) | Ten or shorter if hair regrowth occurred | 2 weeks | 20 weeks | Intralesional injection (20 mm apart) | Double spin method ● 3000 rpm–7 min ● 4000 rpm–5 min |
CaCl2 | 10–30 ml/NR |
| Fawzy et al. (47) | 3 | 4 weeks | 12 weeks | Intralesional injection (0.1 ml/cm2) | Single spin method ● 3000 rpm–10 min |
NR | 10/2–3 ml |
| Case series/Case reports | |||||||
| Donovan (48) | 1 | – | 12 weeks | Intralesional injection | NR | Not used | 120/9 ml |
| Mubki (49) | 4 | 2 weeks | 18 weeks | Intralesional injection (0.1 ml/cm2) | Single spin method ● 1500 G–4 min |
CaCl2 | 18 ml/NR |
| De Vasconcelos et al. (50) | 3 | 3 weeks | 9 weeks | Intralesional injection (2 cm apart) | NR | NR | NR |
| Fonseka et al. (51) | Until a satisfactory response was obtained | 4 weeks | 32 weeks | Intralesional injection (1 cm apart) | Double spin method ● 3000 rpm–10 min ● 2000 rpm–5 min |
NR | 40/10 ml |
| Chhabra and Verma (52) | NR | 2 weeks | 32 weeks | Intralesional injection (0.1 ml/cm2) | Single spin method ● 3000 rpm–10 min |
Calcium carbonate 0.1 ml | 20 ml/NR |
| Pototschnig and Madl (53) | 3 | 6 weeks | 52 weeks | Intralesional injection (1 cm apart at a depth of 2–3 mm) | Single spin method ● 350 G–5 min |
Not used | 30 ml/NR |
| Ekelem et al. (54) | 3 | 6 weeks | 24 weeks | Intralesional injection | NR | NR | NR/NR |
| Ederaine et al. (55) | NR | 4 weeks | 40 weeks | Intralesional injection | NR | NR | NR/5 ml |
G, gravitational force; NR, not reported; PRP, platelet rich plasma; rpm, revolutions per minute.