This is a phase 1/2 single center, pilot study to assess safety and efficacy of allogeneic adipose-derived mesenchymal stem cells (HB-adMSCs) and to evaluate the timing and combination effects of active treatment versus placebo in promoting the recovery of erectile function in patients undergoing radical retropubic prostatectomy (RALP) of localized prostate cancer.

This is a prospective, single-center, double blind, four-arm, pilot study to evaluate safety and effectiveness of allogeneic stem cells promoting the recovery of erectile function in patients undergoing radical retropubic prostatectomy (RALP) of localized prostate cancer.

All participants will be assessed for eligibility Participants will be randomized in a 1:1:1:1 ratio to Arm 1, Arm 2, Arm 3 or Arm 4 using a validated system that automates the random assignment of participant numbers to randomization numbers.

Study participants will be randomized to receive either:

Arm 1 2.00x 10⁸ HB-adMSCCs locally injected into the corpora cavernosa of the penis and along the right and left neurovascular bundle of the penis in the OR at week 1 plus Placebo via IV in clinic at week 12.

Arm 2 Placebo locally injected into the corpora cavernosa of the penis and along the right and left neurovascular bundle of the penis in the OR at week 1 plus 2.00x 10⁸ HB-adMSCs via IV in clinic at week 12.

Arm 3 2.00x 10⁸ HB-adMSCs locally injected into the corpora cavernosa of the penis and along the right and left neurovascular bundle of the penis in the OR at week 1 plus 2.00x 10⁸ HB-adMSCs via IV in clinic at week 12.

Arm 4 Placebo locally injected into the corpora cavernosa of the penis and along the right and left neurovascular bundle of the penis in the OR at week 1 plus Placebo via IV in clinic at week 12.

Study Medication:

1. Stem cells locally injected in the penis: subjects will receive 1.00x 10⁸ HB-adMSCs injection into the corpora cavernosa of the penis and 5.0x10⁷ HB-adMSCs along the right neurovascular bundle and 5.0x10⁷ HB-adMSCs along the left neurovascular bundle during surgery in the Operating Room (OR)
2. Stem cells delivered intravenous: Subject will receive 2.00x10⁸ HB-adMSCs IV at the doctor's office.

The treatment duration will be 2 cycles. Treatment will be administered on Week 1 (in the OR) and on week 12 in the Urology Clinic.

The study duration will be 24 weeks post-surgery.

Inclusion Criteria:

1. Patients scheduled for RALP with Dr. B. Miles at Houston Methodist.
2. Men aged between 40 and 70 (inclusive) years old
3. Localized prostate cancer: Clinical stage T1-T2, N0, M0
4. Gleason score < 7
5. Pre-op IIEF-5 >20 (Appendix A)
6. Testosterone serum: > 300ng/dl with normal Free Testosterone
7. Life expectancy of at least 10 years
8. Performance status of ≤ 2 (Zubrod scale). (Appendix B)
9. Patients must sign an informed consent indicating that they are aware of the investigational nature of the study, in keeping with the policies of the institution
10. Patient is willing to attempt intercourse at least 5 times per month following urinary control after surgery
11. Supportive partner willing to complete sexual survey questionnaire (Appendix D)
12. PDE5 inhibitors like sildenafil, tadalafil, vardenafil and avanafil are permitted pre and post-surgery if participant was taking this for ED at least 6 months before surgery.
13. Patient need cardiac clearance by the cardiologist

Exclusion Criteria:

1. Penile anatomical abnormalities (Peyronie's disease)

2. Hypogonadism

3. Any medication used for androgen ablation (e.g., LHRH agonist or antagonist, anti-androgens, etc.)

4. Patients with AST levels above 40U/L ; ALT levels above 33 U/L and Glucose levels above 180 mg/dl and psychiatric disorders that require medication

5. Previous or current hormonal treatment, chemotherapy, radiation therapy, immunotherapy or another investigational drug.

6. Any previous penile implant or penile vascular surgery

7. Injections of Trimix (combination of alprostadil, papaverine and phentolamine) pre and post-surgery .

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