Considerations for the clinical use of stem cells in genitourinary regenerative medicine

Table 1 In vivo studies for regenerative medicine of urologic tissues (excluding studies using adipose tissue-derived stem cells) (words used in the PubMed research engine (National Library of Medicine): “Urology” “regeneration” “reconstruction” “stem cells”)

Stem cell type	Organ treated	Pathology	Animal model	Ref.
AFSC	Bladder	OAB	Rat	[203,204]
AFSC	Bladder	DUA	Rat	[205]
AFSC	Bladder	PD	Rat	[206]
AFSC	Bladder	Stroke	Rat	[203]
BM-MSC	Bladder	OAB	Rat	[207,208]
BM-MSC	Bladder	pBOO	Rat	[209]
BM-MSC	Bladder	IC/BPS	Rat	[210]
BM-MSC	Bladder	PD	Rat	[206,211]
BM-MSC	Bladder	SCI	Rat	[212-214]
BM-MSC	Bladder	Partial cystectomy	Rat	[215]
BM-MSC	Kidney	Renal regeneration	Mouse	[216]
BM-MSC	Kidney	CKD	Rat	[69,70]
BM-MSC	Kidney	AKI	Rat	[7,71]
BM-MSC	Kidney	AKI	Human	[83]
BM-MSC	Bladder	Partial cystectomy	Rat	[90]
BM-MSC	Urinary sphincter	SUI	Rat	[91]
BM-MSC	Bladder	Hemicystectomy	Dog	[97]
BM-MSC	Bladder	Augmentation	Rat	[98]
BM-MSC	Penis	ED	Rat	[217,218]
BM-MSC	Urethra	Urethroplasty	Rabbit	[103]
DP-SC	Bladder	IC/BPS	Rat	[219]
ESC	Kidney	Reconstruction	Rat/mouse	[88]
ESC-MGE	Bladder	SCI	Mouse	[220]
ESC-MSC	Bladder	IC/BPS	Rat	[221-223]
MDC	Bladder	DUA	Rat	[224,225]
MDC	Bladder	DUA	Mouse	[225]
NPC	Bladder	SCI	Rat	[226-228]
OM-SC	Bladder	SCI	Rat	[229]
Sk-MSC	Bladder	DUA	Rat	[230]
Sk-MSC	Urinary sphincter	SUI	Monkey	[231]
Sk-MSC	Urinary sphincter	SUI	Human	[92-94]
Sk-MSC	Urethra	Urethral defect	Rat	[102]
UCB-MSC	Bladder	OAB	Rat	[232]
UCB-MSC	Bladder	IC/BPS	Rat	[233-235]
UCB-MSC	Bladder	Cerebral Ischemia	Rat	[232]
USC	Bladder	IC/BPS	Rat	[236]
USC	Urethra	Urethral defect	Rabbit	[237]
USC	Penile Cavernous body	ED	Rat	[238]
USC	Kidney	AKI	Rat	[84]
USC	Bladder	Augmentation	Rat	[101]

AKI: Acute kidney injury; ASCs: Adipose-derived stromal/stem cells; BM-MSC: Bone marrow-mesenchymal stem cells; UCB-MSC: Umbilical cord blood-mesenchymal stem cells; USC: Urine derived stem cells; DPSC: Dental pulp stem cells; OAB: Overactive bladder; DUA: Detrusor underactivity; PD: Peyronie’s disease; pBOO: Partial bladder outlet obstruction; IC/PBS: Interstitial cystitis/bladder pain syndrome; SCI: Spinal cord injury; SUI: Stress urinary incontinence.

Table 2 Adipose-derived stromal/stem cells-based preclinical studies for treating urogenital related diseases/pathologies (2016-2021)

Year	Organ/tissue	Disease/method	Animal model	Type of therapy (cell type/host anatomic site)	Cell/molecule concentration	Outcomes	Ref.
2021	Kidney	Renal interstitial fibrosis/unilateral urethral obstruction	Nu/nu mice 6–8 week-old males, n = 40	Injection of genetically modified SC human GDNF-ASCs and non-modified ASCs/intravenous	5 × 105 cells in 150 μL of saline	Improvement of vascular rarefaction/Renal protection against microvascular injuries/Oxidative stress reduction	Li et al[144], 2021
2020		Kidney injury/ischemia-reperfusion	Wistar rats 100-200 g males, n = 28	Injection of SC rat ASCs/tail vein	2 × 106 cells in 1 mL of PBS	Reduction of total tissue damage and urine mineral concentration/ASC anti-inflammatory effects	Changizi-Ashtiyani et al[153], 2020
2020		Kidney injury/ischemia-reperfusion	SD rats 8–12 week-old males, n = N/S	Injection of epididymal rat ASCs/left kidney	2 × 106 cells in 100 μL of decellularized kidney ECMH	Epithelial differentiation of post transplanted ASCs/accelerated repair of renal tubular injury via ASC pro-angiogenic molecules	Zhou et al[152], 2020
2020		Sepsis-induced AKI/cecal ligation and puncture	C57/BL6 mice 6–8 week-old males, n = 140	Injection of SC human ASCs-derived exosomes/tail vein injection	100 μg of exosomes in 200 μL of vehicle solution	Exosome protective functions against AKI/apoptosis and inflammation reduction via Sirtuin-1 pathway regulation	Gao et al[149], 2020
2019		Renal interstitial fibrosis/unilateral ureteral obstruction	Nude mice, n = 12	Injection of SC human GDNF-ASCs/tail vein	5 × 105 cells in 150 μL of vehicle solution	Macrophage transition from inflammatory (M1) to reparative (M2) phenotype/reduction of renal fibrosis and inflammation	Wang et al[143], 2019
2019		Diabetic nephropathy/induced diabetes	C57BL/KsJ db/db mice 8 week-old males, n = 20	Injection of SC murine ASCs-derived exosomes/tail vein	N/S	Attenuation of spontaneous diabetes and nephropathy by reduced proteins levels in the urine of treated mice	Jin et al[148], 2019
2017		Renal interstitial fibrosis/unilateral ureteral obstruction	Wistar rats 6 week-old males, n = 45	Injection of epididymal rat ASCs/tail vein	5 × 106 cells in 1 mL of vehicle solution	Significantly reduced EMT and inflammatory response via TGF-β1 signaling pathway inhibition in treated rats	Song et al[140], 2017
2017		Chronic kidney injury/adenine intoxication	Wistar rats 250 g males, n = 12	Injection of SC human ASCs/tail vein	2 × 106 cells in vehicle solution	Reduction of kidney fibrosis/improved creatine and urea in serum/significantly lower expression of profibrogenic genes in treated rats	Rivera-Valdes et al[141], 2017
2017		Acute kidney injury/ischemia-reperfusion	SD rats 220-250 g males, n = 32	Injection of perinephric human ASCs or SVF/intra-parenchymal	2 × 106 cells in 100 μL of PBS	SVF and ASCs equally improved renal injury by promoting cell proliferation and decreasing tubular injury and cell apoptosis	Zhou et al[146], 2017
2016		Acute kidney injury/ischemia-reperfusion	SD rats 250-300 g males, n = 72	Injection of rat ASCs/tail vein	1 × 106 cells in vehicle solution	Significantly lower kidney injury scores at days 1 and 3 post-treatment/not significant improvement at day 7 post-treatment	Sheashaa et al[145], 2016
2016		Acute kidney injury/IRI	SD rats 320-350 g males, n = 40	Injection of epididymal rat ASCs and ASCs-derived exosomes/intravenous	1.2 × 106 cells + 100 μg of ASCs-derived exosomes	Combined ASCs and exosomes confer higher kidney protection towards IRI than either one alone	Lin et al[147], 2016
2016		Chronic kidney disease/already present	Cats (various sex, age and breeds), n = 8	Injection of allogenic cryopreserved feline ASCs/cephalic vein	2 × 106 cells per kg in vehicle solution	No significant improvement of renal functions between treated and control groups/not adverse side effects noticed using allogenic ASCs	Quimby et al[150], 2016
2018	Urethra	Stress Urinary Incontinence/pudendal nerve transection	SD rats adult females, n = 48	Injection of exosomes derived from SC human ASCs/peripheral urethral	50 μg of exosomes in 50 μL of saline	Increased bladder capacity and leak point pressure/higher muscle fiber and nerve fiber regeneration	Ni et al[171], 2018
2018		Stress Urinary Incontinence/pudendal nerve transaction	SD rats 6-7 week-old females, n = 144	Injection of inguinal rat ASCs/transurethral sphincter	1 × 106 cells in 400 μL of D-Hanks’s solution	ASCs in vivo viability 60 d post-implantation/higher content of striated muscle in the urethra/higher values of leak point pressure	Cui et al[170], 2018
2018		Urethral stricture/N/S	SD rats, N/S	Injection of miR-21 modified SC human ASCs/ urethral wall	1 × 106 cells in 100 μL of saline	miR-27 cells increased epithelium and smooth muscle layer formation compared to normal ASCs/improve the epithelial wound healing microenvironment	Feng et al[168], 2018
2016		Urethral fibrosis/TGF-β1 induced model	SD rats 300 g males, n = 18	Injection of inguinal rat ASCs/urethra	2 × 105 cells in 50 μL of saline	Significantly decreased fibrosis evaluated by reduced collagen type I and III expression	Sangkum et al[167], 2016
2016		Urethral stricture/induced by TGF-β1 and surgical incision	SD rats 300-350 g males, n = 36	Injection of SC human ASCs/urethral wall	1 × 106 cells in 100 μL of PBS	Increased bladder capacity (50%)/wider urethral lumen/decreased expression of fibrosis-related genes	Castiglione et al[166], 2016

AKI: Acute kidney injury; ASCs: Adipose-derived stromal/stem cells; db/db: Spontaneous diabetes; ECMH: Extracellular matrix hydrogel; EMT: Epithelial mesenchymal transition; g: grams; GDNF: Glial-derived neurotrophic factor; IRI: ischemia-reperfusion injury; N/S: Not specified; PBS: Phosphate-buffered saline; SC: Subcutaneous; SD: Sprague-Dawley; SVF: Stromal vascular fraction; TGF-β1: Transforming growth factor-β1.

Table 3 Preclinical studies of urogenital related pathologies/disease using adipose-derived stromal/stem cells in tissue engineering (2016-2020)

Year	Organ/tissue	Approach	Animal model	Substitute implantation (cell type and scaffold/host anatomic site)	Cell concentration per scaffold	Outcomes	Ref.
2020	Kidney	Diabetic nephropathy/unilateral nephrectomy	SDT fatty rats 5-week-old males, n = 21	SC rat ASCs three-layer sheets/renal capsule transplantation	1 × 106 cells in 35-mm culture dish/sheet	14-d survival of transplanted sheets/significantly lower urinary TNF-α levels/maintained renal tubular structure in treated rats	Takemura et al[155], 2020
2018		Kidney reconstruction	Wistar rats 6-8 week-old males	Inguinal rat ASCs seeded onto a rat decellularized kidney/no implantation	1 × 107 cells in 2 ml of culture medium per decellularized kidney	ASCs differentiated into endothelial and tubular cells after 5 d of culture/few cells attached to the scaffold after 10 d	Xue et al[154], 2018
2016	Ureter	Artificial ureter injury/surgical excision	New Zealand white rabbits3.5 kg females, n = 20	Smooth muscle like-cells from SC rabbit ASCs seeded onto ventral aorta/decellularized matrix/graft placed over ureter defect	N/S	Seeded ASCs showed urothelial and smooth muscle-like cells phenotype in the ureter substitute 8 wk after implantation	Zhao et al[165], 2016
2020	Bladder	Complete bladder removal/surgical excision	SD rats 300 g adult females, n = 9	SFP human ASCs seeded onto a decellularized rat bladder matrix/bladder transplantation	1 × 106 cells in 500 μL of cells suspension/bladder scaffold	Acquisition of a smooth muscle-like phenotype of seeded ASCs seeded/ASC paracrine effect increased vascularization and innervation	Moreno-Manzano et al[163], 2020
2020		Sub-totally resected urinary bladder/upper two-thirds bladder excision	Athymic rats 200 g adult females, n = 9	Smooth muscle-like cells from SC human ASCs seeded onto 3-layer PLGA sheet/bladder graft anastomosis	1 × 106 cells mixed with 500 μL of human plasma/scaffold	Complete bladder regeneration and functionality restoration/fusion of smooth muscle-like cells in the regenerated muscular layer	Salem et al[162], 2020
2019		Bladder injury/surgical incision(1 cm)	SD rats 6-week-old females, n = 48	Inguinal rat ASCs cells and PGA combined sheets/bladder patch anastomose	1 × 105 cells/cm2 per sheet reconstruction	Patches promote urothelium, smooth muscle, neural and blood vessel regeneration/restored bladder function	Wang et al[151], 2019
2018		Bladder augmentation/cystotomy incision (1 cm)	SD rats 8 week-old males, n = 34	Inguinal rat ASCs seeded onto PCL-Chitosan scaffold/bladder substitute anastomose	15 × 107 cells/mL per scaffold	Higher smooth-muscle regeneration from ASCs/larger bladder capacity/increased angiogenesis	Zhou et al[161], 2018
2017		Bladder augmentation/surgical incision(1 cm)	SD rats 8 week-old females, n = 46	SC rat ASCs seeded onto an AM-SF scaffold/bladder substitute anastomose	10 × 107 cells/mL in 40 μL of saline per scaffold	Bladder capacity augmentation (30%)/relatively normal micturition pattern/ASC viability after 12 wk of implantation	Wang et al[157], 2017
2017		Bladder augmentation/surgical incision (1 cm)	SD rats 8 week-old males, n = 30	Inguinal rat ASCs seeded onto a BAMG-SF scaffold/bladder substitute anastomosis	50 μL of cell suspension at 1 × 108 cells/mL per scaffold	Higher bladder capacity (2.3-fold)/Enhanced VEGF angiogenic potential by ERK ½ phosphorylation	Xiao et al[160], 2017
2017		Augmentation cystoplasty/surgical incision (1 cm)	SD rats 8 week-old males, n = 30	Rat ASCs encapsulated in an ADA/GEL seeded onto a porcine BAMG/bladder substitute anastomosis	100 μL of encapsulated cells at a 1 × 106/mL concentration per scaffold	Morphological bladder restoration by enhanced scaffold degradation/enhanced VEGF-mediated angiogenesis and smooth muscle regeneration in treated rats	Xiao et al[210], 2017
2016		Bladder augmentation/surgical incision (1 cm)	SD rats immunocompetent 36 week-old males, n = 30	Inguinal rat ASCs seeded onto a porcine BAMG/Bladder substitute anastomosis	15 × 107/mL cell suspension per scaffold	Greater bladder capacity in experimental group/equal urothelial regeneration in the treated and non-treated groups at 4- and 14-wk post-implantation	Zhe et al[156], 2016
2016		Partial cystectomy/half upper bladder transection	Beagle dogs 10-12 Kg males, n = 12	Human ASCs seeded onto a whole porcine BAMG/scaffold grafted onto bladders’ dome	1 × 105 cells per cm2 of each scaffold	Complete urothelial coverage of seeded and unseeded bladder after 6 mo/higher capillary density and smooth muscle organization in treated dogs’ bladder	Hou et al[159], 2016
2020	Urethra	Urethral injury/surgically induced	New Zealand white rabbits 9-week-old males, n = 24	SC rabbit ASCs seeded onto a human DAM scaffold/urethral graft	1 × 106 cells per scaffold	Higher number of urethras healed following seeding of ASCs onto DAM	Hariastawa et al[172], 2020
2020		Urethral injury/surgically induced (2 cm × 0.6 cm)	New Zealand white rabbits males, n = 15	Inguinal rabbit ASCs seeded in a nanofibrous scaffold/graft placed over urethral defect	1 × 107 cells per scaffold	Hypoxia preconditioning of ASCs increased urethral lumen diameter/preserved morphology/enhanced angiogenesis	Wan et al[173], 2020

ADA-GEL: Alginate dialdehyde-gelatin; AM-SF: Autologous myofibroblast-silk fibroin; ASCs: Adipose-derived stromal/stem cells; BAMG-SF: Bladder acellular matrix graft-silk fibroin; bFGF: Basic fibroblast growth factor; DAM: Dried amniotic membrane; g: gram; Kg: Kilogram; N/S: Not specified PCL: Polycaprolactone; PGA: Polyglycolic acid; PLGA: Poly(lactid-co-glycolic acid); SC: Subcutaneous; SD: Sprague-Dawley; SDT: Spontaneously diabetic Torii; SFP: Suprapatellar fat pad; TNF-α: Tumor necrosis factor-α; VEGF: Vascular endothelial growth factor.

Table 4 Preclinical studies for treatment of urogenital related diseases using dedifferentiated fat cells

Year	Disease/injury	Animal model	Type of therapy (cell type/injection site)	Cell concentration	Outcomes	Ref.
2016	VUR	SD rats 8 week-old females weighing 200 g, n = 10	Injection of undifferentiated rat DFAT cells/bilateral vesicoureteral junction	1 × 106 cells in 30 μL of saline	Significant amelioration of VUR in treated rats/nephroprotective effects in rats	Ikado et al[178], 2016
2015	Immunologically induced glomerulonephritis and adriamycin induced nephropathy	Wistar rats, males weighing 250 g, n = 64	Injection of undifferentiated rat DFAT cells/RA or TV	1 × 106 cells in 20 μL of saline	TV DFAT cell injection showed lower proteinuria and renal degeneration than direct cell implantation/DFAT immunosuppressive effects significantly reduced glomerulonephritis in treated rats	Maruyama et al[177], 2015
2011	Urethral sphincter injury by VD	SD rats 8 week-old females, n = 16	Injection of undifferentiated rat DFAT cells/paraurethral connective tissue at mid-urethra	1 × 106 cells in 20 μL of saline	Sphincter muscle regeneration by DFAT cell therapy/improvement of “lowered leak point”	Obinata et al[176], 2011
2009	Cryo-injured bladder wall (2 mm diameter)	C57BL/6 mice 8-9 week-old males, n = 10	Injection of smooth muscle-like cells differentiated from human DFAT cells/bladder wall	1 × 106 cells in 20 μL of Hanks’ balanced solution	DFAT differentiation potential into smooth muscle-like cells/approximately 2-fold higher αSMA expressing cells in scar tissue 30 d post-injection in treated mice	Sakuma et al[175], 2009

αSMA: alpha smooth muscle actin; DFAT: Dedifferentiated fat; RA: Renal artery; SD: Sprague-Dawley; TV: Tail vein; VD: Vaginal distension; VUR: Vesicoureteral reflux.