Introduction

Erectile dysfunction (ED) is defined as the persistent inability to achieve or maintain an erection sufficient for satisfactory sexual performance (1). The prevalence of ED increases with age. The Global Study of Sexual Attitudes and Behaviors, which included populations from 29 countries across five continents, reported a prevalence of 20.6% among men aged 40–80 years (2). In Asia, the prevalence ranges from 7 to 15% in men aged 40–49 years and increases to 39 to 49% among those aged 60–70 years (3).
According to current European Association of Urology (EAU) and American Urological Association (AUA) guidelines, phosphodiesterase type 5 inhibitors are the first-line pharmacologic treatment for ED and have demonstrated effectiveness in many patients (4). However, a substantial proportion of individuals, particularly those with underlying comorbidities or severe endothelial dysfunction, show suboptimal response and require second- or third-line therapies. Among these, regenerative therapies such as platelet-rich plasma (PRP) (5), low-intensity extracorporeal shockwave therapy (Li-SWT) (6), and stem cells therapy (SCT) have garnered increasing attention due to their potential to address the underlying pathophysiology of ED rather than merely alleviating symptoms (7).
Each modality exerts its therapeutic effect through distinct biological mechanisms. PRP delivers autologous growth factors that promote angiogenesis, tissue repair, and collagen remodeling (8); Li-SWT stimulates mechanotransduction pathways leading to neovascularization, cellular proliferation, and endothelial regeneration (9); SCT, though still largely investigational, is thought to restore erectile tissue function by differentiating into endothelial and smooth muscle cells and promoting paracrine-mediated tissue repair (10, 11).
However, both the EAU and AUA guidelines currently classify these therapies as experimental and do not recommend their routine clinical use due to insufficient high-quality evidence, despite recognizing them as emerging approaches that warrant further investigation (4). Moreover, none of these modalities have received specific approval from the U.S. Food and Drug Administration for the treatment of ED. While numerous systematic reviews and meta-analyses have assessed these therapies individually (12-14), or in combination (15), inconsistencies remain regarding their comparative efficacy, duration of benefit, and clinical applicability. Moreover, head-to-head comparisons are limited, and the durability of treatment effects over time is not well characterized. Therefore, we conducted a systematic review and meta-analysis to evaluate the effects of PRP, Li-SWT, and SCTs on erectile function in adult men with ED using standardized patient-reported outcomes, including the International Index of Erectile Function (IIEF-5) and Erectile Hardness Score.

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Materials and Methods

Search strategy and eligibility criteria
This systematic review is based on the Preferred Reporting Items for Systematic Review and Meta-analysis (PRISMA), which can be accessed through https://prisma-statement.org//. A comprehensive literature search was performed across four electronic databases: PubMed, Scopus, ScienceDirect, and ProQuest, covering publications from inception to May 31, 2025. The search strategy utilized combinations of the following keywords: “platelet-rich plasma,” “low-intensity shockwave therapy” or “Li-SWT,” “mesenchymal stem cells,” and “erectile dysfunction.” Search filters were applied to include studies written in English, available in full text, and classified as controlled clinical trials.
Studies were considered eligible if they involved adult male patients with ED of any etiology and assessed regenerative therapies—specifically PRP, Li-SWT, or SCT—with erectile function outcomes measured using standardized tools such as the IIEF.

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Study selection
The inclusion criteria were controlled trial studies involving: (1) adult patients with ED of any cause; (2) treatment with PRP, Li-SWT, or SCT; and (3) the mean difference (MD) in the IIEF as an outcome. Studies that did not include human participants, reviews, editorials, case reports, and studies without comparative or quantitative outcome data were excluded. The inclusion criteria were primarily limited to readily accessible and available studies for review and controlled trials that met the PICO framework (Table 1).

 

Table 1.

PICO criteria
ED, erectile dysfunction; EDV, end-diastolic velocity; IIEF, International Index of Erectile Function; Li-SWT, low-intensity shockwave therapy; PRP, platelet-rich plasma; PSV, peak systolic velocity

Two independent reviewers screened all titles, abstracts, and full texts to determine eligibility. Any disagreements were resolved through discussion or consultation with a third reviewer. The protocol for this systematic review was registered in the PROSPERO database (CRD420251083791).

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Data extraction
Data extraction from the selected articles was conducted by two authors, and any discrepancies were resolved through a consensus-based approach. The relevance of the articles was evaluated through careful examination of their titles and abstracts. The variables extracted from the articles included the name of the first author, year of publication, type of intervention, control conditions, method of administration, and study outcomes. In cases where data were not available, the initial writers of the selected articles were contacted to acquire additional details or extra information.

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Risk of bias assessment
The risk of bias in the included studies was assessed using the ROBINS-I tool from the Cochrane Collaboration, which evaluates seven domains: (1) confounding, (2) participant selection, (3) intervention classification, (4) deviations from intended intervention, (5) missing data, (6) outcome measurement, and (7) selection of reported results. The assessment categorized studies as having low risk, high risk, or concerns regarding bias.

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Statistical analysis
Data analysis was performed using RevMan 5.3 (The Cochrane Collaboration, London, UK) software, developed by the Cochrane Collaboration. The MDs between the intervention and the control groups were calculated and are shown as a forest plot. Results were considered statistically significant if the p value was <0.05. The I2 statistic was used to check the extent to which the results varied between studies. If the p value was >0.05 and I2 was <50%, this indicated low variation; therefore, a fixed-effects model was used. If I2 was >50% and the variation was significant, a random-effects model was applied.
 

Results

Study selection
The initial database search across PubMed, Scopus, ScienceDirect, and ProQuest yielded a total of 6955 records. After removing 112 duplicate entries using automated filtering tools, 6843 records remained for screening. Based on title and abstract review, 6669 records were excluded due to irrelevance to the topic. Of the remaining 174 full-text articles, 5 were excluded due to inaccessible full texts, and 156 were excluded for not reporting the outcomes of interest. Ultimately, 13 studies met the inclusion criteria and were included in the qualitative synthesis, with 11 included in the meta-analysis. The study selection process is summarized in the PRISMA flow diagram (Figure 1).

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Figure 1.

PRISMA flow chart. RCT, randomized controlled trial.

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Risk of bias assessment was performed using the ROBINS-I tool. Among the included studies, eight were rated as having low risk of bias, one had some concerns, and four were assessed as having high risk of bias. Studies at high risk were retained in the analysis, as they provided relevant data points across multiple post-intervention timeframes. Notably, these studies often demonstrated greater variation in effect sizes at later follow-up periods. A test for funnel plot asymmetry did not demonstrate a statistically significant small-study effect (t=1.66, df=8, p = 0.1345). The estimated intercept indicated a potential bias of 1.98 (SE=1.19); however, this did not reach statistical significance. Substantial residual heterogeneity was observed, with a multiplicative residual heterogeneity variance (τ2) of 4.67. The analysis was performed using inverse-variance weighting, with the standard error included as the predictor (Figure 2).

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Figure 2.

Funnel plot for assessment of publication bias.

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Eligible study characteristics
Thirteen studies published between 2014 and 2025 were included, involving a total of 494 patients diagnosed with ED. The studies originated from various countries and were categorized based on the type of regenerative therapy investigated: SCT (two studies), PRP (five studies), and Li-SWT (six studies). Only the PRP and Li-SWT groups were included in the meta-analysis due to comparability in outcome measures. The SC group was evaluated narratively in the systematic review. Detailed characteristics of the included studies are presented in Table 2.

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Table 2.

Study characteristics of included studies
ED, erectile dysfunction; EDV, end-diastolic velocity; EFD, energy flux density; EHS, Erection Hardness Score; IIEF, International Index of Erectile Function; Li-SWT, low-intensity shockwave therapy; MSCs, mesenchymal stem cells; PRP, platelet-rich plasma; PSV, peak systolic velocity; RCT, randomized controlled trial; RI, resistive index; SWs, shockwaves.
 

PRP and Li-SWT in 3 months
A meta-analysis was conducted to evaluate the effects of PRP and Li-SWT on erectile function at 3 months post-treatment, with each intervention analyzed separately against control groups. In the PRP subgroup, five studies including 156 participants in the intervention arms and 104 participants in the control arms were analyzed. The pooled MD in IIEF scores was 1.44 [95% confidence intervals (CI) 0.21–3.09]; however, this improvement did not reach statistical significance (p = 0.09). Substantial heterogeneity was observed among the included studies (I2=83%).

In the Li-SWT subgroup, six studies comprising 206 participants in the intervention arms and 146 participants in the control arms demonstrated a statistically significant improvement in IIEF scores compared with controls, with a pooled MD of 3.39 (95% CI 2.36–4.42; p < 0.001). Low heterogeneity was noted within this subgroup (I2=9%) (Figure 3).

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Figure 3.

Forest plot for PRP and Li-SWT in 3 months. CI, confidence interval; Li-SWT, low-intensity shockwave therapy; PRP, platelet-rich plasma; SD, standard deviation.

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PRP and Li-SWT in 6 months
At 6 months post-treatment, five studies in the PRP subgroup (155 intervention participants vs. 92 controls) showed a statistically significant improvement in IIEF scores, with a pooled MD of 2.03 (95% CI 0.26–3.81, p = 0.02). Nevertheless, substantial heterogeneity was noted (I2=83%). In contrast, the Li-SWT subgroup included three studies involving 98 intervention and 161 control participants. The pooled MD was 2.59 (95% CI −1.82 to 6.99), which was not statistically significant (p = 0.25), with high heterogeneity (I2=87%) (Figure 4).
 

​Figure 4.

Forest plot for PRP and Li-SWT in 6 months. CI, confidence interval; Li-SWT, low-intensity shockwave therapy; PRP, platelet-rich plasma; SD, standard deviation.

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Discussion

Summary of the main findings
This systematic review and meta-analysis assessed the efficacy of regenerative therapies—namely PRP, Li-SWT, and SCT—in improving erectile function. Among the 13 included studies, 11 were randomized controlled trials and 2 were non-randomized. Quantitative analysis revealed that both PRP and Li-SWT were associated with improvements in IIEF scores at 3 months post-treatment. Notably, Li-SWT demonstrated a more pronounced effect at 3 months, while PRP showed a statistically significant benefit at 6 months. SCT, although excluded from the meta-analysis due to limited eligible trials, demonstrated promising outcomes in the narrative synthesis. These findings underscore the potential of regenerative therapies as alternative or adjunctive options for patients with ED, particularly when conventional pharmacotherapy fails or is not well tolerated.

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The role of PRP in ED patients
PRP is an autologous biological product derived from a patient’s own blood, enriched with growth factors such as platelet-derived growth factor, transforming growth factor-β, and vascular endothelial growth factor (VEGF) (16). These factors promote angiogenesis, endothelial proliferation, and smooth muscle regeneration, key components in restoring erectile function (17).
Although PRP, Li-SWT, and SCTs are hypothesized to promote angiogenesis and cavernous tissue regeneration, current clinical studies have not yet provided direct evidence confirming these biological mechanisms in human subjects. Most available data focus on patient-reported outcomes rather than on objective tissue-level or molecular endpoints.
In our analysis, PRP did not yield statistically significant improvements in IIEF scores at the 3-month mark, although a trend toward benefit was noted. However, at 6 months, the pooled analysis demonstrated a significant improvement, supporting the notion that the regenerative effect of PRP is gradual and sustained over time. This delay may be attributed to the time required for neovascularization, endothelial remodeling, and neural regeneration to manifest clinically (16).
In Doppler ultrasound assessments, PRP has been associated with improved peak systolic velocity (PSV) and end-diastolic velocity (EDV), consistent with enhanced penile hemodynamics. The increased expression of endothelial nitric oxide synthase and nitric oxide following PRP therapy may further contribute to vascular smooth muscle relaxation and improved erectile rigidity (18). Although minor local pain (e.g., Visual Analog Scale 2.6 vs. 2.2) has been reported, PRP remains well tolerated with no significant adverse events such as bleeding or fibrosis (19).

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The role of Li-SWT in ED patients
Li-SWT has gained traction as a non-invasive regenerative treatment for ED. It works by inducing mechanical stress that triggers angiogenesis, SC recruitment, and tissue regeneration (20, 21). Our findings showed that Li-SWT significantly improved IIEF scores at 3 months with low heterogeneity among studies, suggesting a consistent early therapeutic effect. However, the benefit appeared to diminish at 6 months, with no statistically significant difference compared to controls.
This decline may be explained by a plateau in vascular remodeling or the waning of initial regenerative signaling. Some studies have shown a decline in IIEF scores after 6 months, while others reported stabilization (22, 23). Variability in treatment protocol, energy density, number of sessions, and follow-up durations may have contributed to inconsistent long-term outcomes (24, 25).
Objective measures of vascular function such as PSV and EDV did not consistently support a long-term benefit of Li-SWT, with several studies showing only short-term hemodynamic improvements. This highlights the need for standardized outcome measurement and longer follow-up periods in future studies (26, 27).

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The role of SC in ED patients
Although SCT was not included in the meta-analysis, two controlled studies provided encouraging data. Mesenchymal stem cells, particularly from adipose tissue or bone marrow, are capable of differentiating into endothelial and smooth muscle cells within the corpus cavernosum (28). Intracavernosal administration facilitates targeted delivery to damaged erectile tissue (29, 30).
Reported benefits included significant improvements in IIEF scores and penile hemodynamics, particularly in diabetic patients (31). The therapeutic mechanism appears to be mediated through paracrine effects—enhancing angiogenesis, tissue repair, and immunomodulation—rather than direct engraftment alone. VEGF expression and increased endothelial content within the corpus cavernosum have been proposed as surrogate markers of successful tissue regeneration (32). Despite promising early results, SCT for ED remains investigational. Further high-quality randomized trials with standardized cell types, dosages, and follow-up periods are required to clarify its role relative to PRP and Li-SWT.

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Safety considerations and long-term outcomes
Most included studies had relatively short follow-up periods and provided limited data on treatment-related complications. Several studies reported no significant adverse events associated with PRP, with no cases of penile fibrosis or injection-related complications such as hematuria, local petechial hemorrhage, or ecchymosis (33, 34). Similarly, Li-SWT demonstrated a favorable safety profile, with no reported adverse events during follow-up periods of up to 12 months (25). Studies evaluating SCT also reported no major local or systemic adverse effects, including bleeding, bruising, pain, swelling, temperature-related changes, erythema, urticaria, or priapism at the injection site (35). Nevertheless, despite the generally favorable short-term safety profiles observed across all modalities, the lack of long-term follow-up and systematic adverse event reporting precludes definitive conclusions regarding long-term safety, durability of therapeutic effects, and the risk of delayed complications.

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Strengths and limitations
This review contributes to the growing body of evidence supporting regenerative therapies for ED. Unlike prior reviews, we included the most up-to-date studies and distinguished between short- and mid-term outcomes of PRP and Li-SWT. Moreover, we synthesized both subjective and objective outcomes across diverse populations. Nevertheless, several limitations must be acknowledged. Considerable heterogeneity existed among the included studies in terms of patient characteristics, treatment protocols, and outcome measures. Many included studies were non-randomized, involved small sample sizes, and had short follow-up durations, with potential risks of bias arising from non-blinded study designs and selective outcome reporting. The lack of direct head-to-head trials between PRP, Li-SWT, and SCT restricts definitive comparative conclusions. Additionally, a significant limitation is the inability to categorize outcomes based on the cause of ED, primarily due to the scarcity of studies and the inconsistency in reporting the causes. To bridge this gap, future well-designed trials with populations defined by etiology are necessary. Research should focus on standardized protocols, extended follow-up periods, and direct comparisons of regenerative therapies. A network meta-analysis may also be useful to rank the efficacy and durability of each approach for different subgroups of ED patients.

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Novelty and contribution to existing literature
While previous systematic reviews have examined regenerative therapies for ED, this study provides several key contributions that distinguish it from earlier work. First, unlike prior meta-analyses that grouped all interventions together or focused solely on one modality, our review presents a direct comparison between PRP and Li-SWT using time-specific subgroup analyses at 3 and 6 months. This temporal stratification highlights the differential onset and durability of treatment effects, with Li-SWT demonstrating superior short-term outcomes and PRP showing more sustained benefits over time.

Second, this review integrates both subjective (IIEF scores) and objective vascular parameters (PSV and EDV from Doppler ultrasound) to provide a more comprehensive evaluation of treatment efficacy. Few prior reviews have included or correlated these physiological outcomes with clinical endpoints.

Third, our review includes the most up-to-date controlled trials published up to May 2025, incorporating new evidence that has not yet been included in previous analyses, including studies from diverse populations and clinical settings. By synthesizing these newer trials, we provide a refreshed perspective on the evolving role of regenerative therapies in ED management.

Finally, although SCT was not included in the meta-analysis, its inclusion in the narrative synthesis addresses an emerging area of interest and highlights the need for further research. Together, these contributions provide clinicians and researchers with clearer guidance on the comparative timing, durability, and clinical utility of PRP and Li-SWT in the management of ED.
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Conclusion

Regenerative therapies have been investigated as potential interventions for ED; however, the available evidence remains limited and heterogeneous. Both Li-SWT and PRP were associated with improvements in erectile function compared with control conditions across several follow-up time points, although no direct head-to-head comparisons were available. Evidence for SCT is preliminary and insufficient to support definitive conclusions. Given these limitations, the current findings should be interpreted with caution, and further well-designed randomized controlled trials with standardized treatment protocols and comprehensive long-term efficacy and safety assessments are required to better define the clinical role of these regenerative approaches.

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Author contributions

AGRC led in conceptualization, formal analysis, and in writing of the original draft. DSW led in supervision and in reviewing & editing of the original draft. Both authors equally contributed to data curation, methodology and validation.

 

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