Therapeutic Potential of Adipose-Derived Stem Cells-Based Micro-Tissues in a Rat Model of Postprostatectomy Erectile Dysfunction
Yongde Xu PhD, Ruili Guan PhD, Hongen Lei MD, Huixi Li MD, Lin Wang PhD, Zhezhu Gao MD, Weidong Song PhD, and Zhongcheng Xin MD
ONLINE: July 15, 2014 – The Journal of Sexual Medicine
Erectile dysfunction (ED) is the most common long-term complication following radical prostatectomy and can result from both neurogenic and vasculogenic factors. While phosphodiesterase type 5 (PDE5) inhibitors can help, they are not always effective for patients who have been treated for clinically localized prostate cancer.
Other approaches for restoring erectile function, such as neurotrophic factors and vasoactive agents, have been investigated, but are still considered experimental.
Past research has also looked at stem cells, but single-cell injection strategies have had a poor retention rate because of high cellular washout and low cellular survival.
Combinatory methods like synthetic scaffolds and genetic modifications have also been tried, but have not been effective.
Assembling cells onto micro-tissues before transplanting them could be a more viable strategy than single-cell methods. Using adipose-derived stem cells (ADSCs) could be a promising route, as they are easily obtained and can be expanded in vitro. In this study, the authors investigated the feasibility and mechanism of ADSCs-based micro-tissues (MTs) in the treatment of ED in rats who have undergone cavernous nerves (CN) injury.
Methods and Materials
Eighty 12-week-old Sprague-Dawley rats were used in this study. All rats underwent para-testicular fat harvest before they were divided into groups.
Ten randomly-selected rats that had a midline abdominal incision with no CN crush injury formed the sham group. They were injected with a phosphate buffer solution (PBS).
The remaining 70 rats underwent bilateral CN crush and were divided as follows:
• Crush group: 10 rats that treated with PBS
• ADSCs group: 30 rats that received single-cell ADSC suspension.
• MTs group: 30 rats treated with MTs.
In the ADSCs group and the MTs group, 5 rats each were euthanized at 1, 3, 7, and 14 days. At the 28-day mark, penile tissues of the remaining rats were harvested and analyzed for 5-ethynyl-2-deoxyuridine (EdU) + cells; the rats were examined for erectile function (intracavernous pressure response) before their tissues were harvested.
Generation and Characterization of MTs
ADSCs went from a loose network to a smooth-edged spheroid shape in about three days, at which point the mean spheroid diameter was 178.33 ± 11.06 μm.
The MTs were of a round-oval shape. Cells within the spheroids were embedded in matrix. The spheroid surface had a compacted layer of epithelium-like cells with an elongated pattern. Immunofluorescent staining showed that MTs also expressed certain proteins.
The MTs expressed nerve growth factor, vascular endothelial growth factor, CXCR4 (chemokine receptor type 4), Wnt5a, and collagen IV.
More EdU + ADSCs were retained in the corpus cavernosum in the MTs group when compared to the ADSCs group.
Erectile function was evaluated 28 days after surgery. Both the ADSCs group and the MTs group had partial to significant recovery of erectile response.
Intracavernous injection of MTs resulted in significant restoration of the erectile function and histopathological changes compared to the ADSCs group.
The authors noted that in this study (MTs generated by a hanging drop method), more EdU + cells were retained in the MTs group than in the ADSCs group. Also, all EdU + cells in these two groups occurred in the perisinusoidal connective tissue. The EdU cells did not show signs of differentiation into smooth muscle and endothelial cells. This result suggests that paracrine action is at work.
The researchers added that the subculturing of SCs with pronged time in vitro leads to changes in their phenotypes. Past research has suggested that manipulating SCs in culture before transplanting them might improve their effectiveness.
Future research should examine the changes that occur when ADSCs aggregate into spheroids, the authors said.
Overall, the authors concluded, “IC-injected MTs resulted in a better restoration of erectile function than traditional single-cell strategy. The underlying mechanisms of recovery appear to involve enhanced cellular retention in the penis and upregulation of some paracrine factors.”