Introduction

Erectile dysfunction (ED) is a prevalent condition affecting approximately 1 in 4 men, with its incidence on the rise.¹ Guideline-supported medical treatments for ED primarily focus on transient vasodilation through augmentation of the nitric oxide pathway.² While these treatments offer symptomatic relief, they are unable to reverse the underlying pathology. Additionally, many men discontinue medical therapies due to lack of efficacy and side effects.^3,4 Therefore, there is growing interest in restorative therapies such as platelet-rich plasma (PRP) and shockwave therapy that hold the potential to reverse the underlying pathology and restore natural spontaneous erections.⁵ PRP, an autologous blood product with a high concentration of platelets, has been utilized in various fields for its regenerative properties, including promoting healing and tissue repair. However, despite its use in other medical applications, there is a scarcity of clinical evidence supporting its efficacy in treating ED.

Objective

The objective of this prospective, randomized, double-blind, placebo-controlled clinical trial was to assess the clinical efficacy of PRP for ED. The study aimed to determine if PRP injections could improve erectile function in men with mild to moderate ED compared to placebo.

Methods

The study was conducted at the outpatient clinic of the Desai Sethi Urology Institute in Miami, Florida, United States. The study protocol was approved by the Institutional Review Board and registered on ClinicalTrials.gov. A total of 61 men with ED were recruited between May 2020 and August 2022. The participants underwent thorough screening, including medical history, physical examination, questionnaires (International Index of Erectile Function-Erectile Function [IIEF-EF] and Sexual Encounter Profile), measurement of serum testosterone levels, HbA1c, and complete blood count. Baseline penile duplex ultrasound was performed to assess penile vascular parameters. The participants were sequentially randomized in a 1:1 ratio to receive either PRP or placebo injections (Figure 1). Intracavernosal injections were administered in 2 sessions, 28±7 days apart. PRP was obtained through centrifugation and separation of autologous blood using the Arthrex Angel PRP system. The treatment group received PRP injections, while the placebo group received saline injections (Figure 2). The study was double-blind, with only 1 researcher aware of the treatment allocations who was not involved in data collection or outcome analysis.

Figure 1. Patient flow diagram. FU indicates follow-up; IIEF, International Index of Erectile Function; PRP, platelet-rich plasma.

Figure 2. Platelet-rich plasma/placebo injection into corpus cavernosum.

Outcomes

The primary outcome of the study was the number of men meeting the minimum clinically important difference (MCID) at 1 month after the second injection. MCID was defined as an increase of 2 for mild ED (starting IIEF-EF 17-25) and 5 for moderate ED (starting IIEF-EF 11-16). Secondary outcomes included changes in IIEF-EF scores, penile vascular parameters, and adverse events. Follow-up assessments were conducted at 1, 3, and 6 months after the last injection to evaluate long-term side effects and durability of response.

Results

A total of 61 men were randomized, with 28 in the PRP group and 33 in the placebo group. Complete 1-month data were available for 24 men in the PRP group and 28 men in the placebo group. Additionally, complete 6-month data were obtained for 20 men in the PRP group and 24 men in the placebo group. Baseline demographics and characteristics were similar between the 2 groups, except for a higher prevalence of prediabetes in the placebo group. The analysis of IIEF-EF scores from baseline to 1 month showed a change from 17.4 (15.8-19.0) to 21 (17.9-24.0) in the PRP group, compared to 18.6 (17.3-19.8) to 21.6 (19.1-24.1) in the placebo group. However, this difference was not statistically significant (P = .756). The percentage of men meeting MCID was 58.3% in the PRP group compared to 53.6% in the placebo group. There were no significant differences in adverse events between the 2 groups (see Table), and no serious adverse events were reported. Moreover, there were no significant differences in mean penile Doppler parameters between baseline and 6 months, or between the PRP and placebo groups.

Limitations

This study has several limitations. First, the sample size was relatively small, which may have influenced the statistical power and generalizability of the findings. Second, the follow-up period was limited to 6 months, which may not have allowed for a comprehensive assessment of long-term efficacy and safety. Third, the study focused on men with mild to moderate ED, and the results may not be applicable to those with severe ED. Lastly, there was potential for bias in the allocation of treatment due to the single researcher responsible for preparing and administering the injections.

Conclusion

The results of our prospective, double-blind, randomized, placebo-controlled clinical trial suggest that 2 injections of intracavernosal PRP separated by 1 month in men with mild to moderate ED is safe but no more efficacious than a placebo.

Interpretation for Patient Care

The findings of this study suggest that PRP injections did not provide a significant improvement in erectile function compared to placebo at 1 month after treatment. However, there was a trend towards improvement in the PRP group at 3 and 6 months. These results should be interpreted with caution due to the limitations of the study. Further research with larger sample sizes and longer follow-up periods is necessary to determine the potential benefits of PRP as a restorative therapy for ED. Nonetheless, the study contributes to the existing knowledge on treatment options for ED and provides important objective data.