Stromal Vascular Fraction and Amniotic Epithelial Cells: Preclinical and Clinical Relevance in Musculoskeletal Regenerative Medicine

Table 6

In vitro, in vivo, and clinical studies on AECs in tendon regeneration.

Experimental model	Treatment groups	Evaluations	Results	Ref
In vitro: oAECs (); Tenocytes () or tendons from heel of adult sheep (2-3 yrs) or fetus sheep (2-3 mo)	Group 1: AECs; Group 2: AECs+fetal tenocytes; Group 3: AECs+adult tenocytes; Group 4: AECs+fetal tendons; Group 5: AECs+adult tendons	AEC proliferation; AEC migration; AEC telomere analysis; RT-PCR (COLL I, COLL III); IHC (OCN, TNMD, and SCXB)	7 days; Group 4: ↑ AEC migration than group 1; 2 wks; Groups 3 and 5: ↓ AEC proliferation than group 1; 1 mo; Groups 2 and 4: ↑ AEC proliferation, OCN, TNMD, and SCXB proteins than group 1; Group 4: ↓ TEA, TEF, and MEAND than group 1; Groups 2-5: ↑ COLL I gene expression than group 1; Group 3: ↓ COLL III gene expression than group 1; Groups 3 and 5: ↓ TNMD protein than group 1	[70]
In vivo: 15 horses with acute SDFT monolateral injuries; oAECs () from slaughtered sheep at 3 mo of pregnancy	Group 1: healthy tendons; Group 2: AECs	Histology; IHC (COLL III, COLL I, and Ki-67)	2 mo; Group 2: ↓ COLL III protein; ↑ COLL I, Ki-67 proteins than group 1, no immunological reaction	[71]
In vivo: 6 adult horses (3-7 yrs) with acute or chronic SDFT tendinopathy in the midmetacarpal region; oAECs () from slaughtered sheep at 3 months of pregnancy	Group 1: AECs	Ultrasonography; Histology	6 mo; Group 1: cross-sectional area similar to an healthy tendon, collagen fibers parallel to the longitudinal axis of the tendon, no neovascularization than presurgery	[72]
In vivo: 23 sheep (40 kg) with a bilateral full-thickness FDST hole (3 mm diameter); Allogenic oAECs () from slaughtered sheep at 3 months of pregnancy	Group 1: FG; Group 2: AECs+FG	Histology; RT-PCR (COLL I, COLL III); Histomorphometry; Biomechanics	2 wks; Group 2: ↑ tendon microarchitecture than group 1; 1 mo; Group 2: ↑ tendon microarchitecture, proliferation, COLL I gene expression, maximum failure load, stiffness; ↓ VA, leukocyte infiltration, cellularity, COLL III gene expression than group 1	[73]
In vivo: 3 adult sheep (50 kg) with bilateral defect in the Achilles tendon middle portion; Allogenic oAECs () from slaughtered sheep at 60-80 days of pregnancy	Group 1: no treatment; Group 2: AECs	Histology	1 mo; Group 2: absent inflammation-proliferating cells, collagen fibers started to be oriented along a longitudinal axis; Group 1: no tendon healing, no proliferating cells, nonorganized collagen fibers	[74]
In vivo: 18 Appenninica breed sheep (2 yrs) with a full-thickness hole in FDST (3 mm diameter); Allogenic oAECs ()	Group 1: FG; Group 2: FG+oAECs	Histology; IHC (COLL I, CD45, CD68, CD86, and MMR/CD206); RT-PCR (CD86, CD206, YM1, IL10, and IL12b)	7, 14, and 28 days; Group 2: ↑ tissue organization; ↓ leukocyte infiltration, IL12 b gene expression than group 1; 14 and 28 days; Group 2: ↓ macrophage infiltration, CD86 gene expression, CD86 positive cells; ↑ IL10 gene expression than group 1; 28 days; Group 2: ↑ COLL I; ↓ cellularity, YM1 gene expression, CD206-positive cells than group 1	[75]
In vivo: 29 adult sheep (2 yrs) with bilateral Achilles tendon defects (5 mm diameter); hAECs ()	Group 1: FG; Group 2: FG+hAECs	RT-PCR (COLL I, COLL III, TNMD, THBS4, CD206, IL10, VEGF, CD68, IL12b); IHC (COLL I, COLL III, VEGF); Histology; Biomechanics (maximum load, stiffness)	1 mo; Group 2: rapid recovery of the tissue; sporadic edema; regular longitudinal profile; ↑ maximum failure load; stiffness; regularly arranged fibers; COLL I gene expression and protein, TNMD, THBS4, CD206, and IL10 gene expression; ↓ COLL III and VEGF gene expression and protein, CD86, and IL12b gene expression than group 1	[76]

Abbreviations: hSVF = human stromal vascular fraction; hBMSCs = human bone marrow mesenchymal stem cells; yrs = years; hrs = hours; wks = weeks; BMSCs = bone marrow mesenchymal stem cells; SVF = stromal vascular fraction; ALP = alkaline phosphatase; RT-PCR = reverse transcriptase-polymerase chain reaction; RUNX2 = runt-related transcription factor 2; COLL = collagen; OSX = Osterix; hADSCs = human adipose-derived mesenchymal stem cells; ADSCs = adipose-derived mesenchymal stem cells; mm = millimeters; BA/TA = bone area/tissue area; PLCL = poly(L-lactide-co-caprolactone); NM = normal medium; CM = chondrogenic medium; OM = osteogenic medium; SOX = sex-determining region Y boxes; OCN = osteocalcin; ACAN = aggrecan; mo = months; IHC = immunohistochemistry; Micro-CT = microcomputed tomography; HA = hydroxyapatite; cm = centimeters; BV/TV = bone volume/tissue volume; CD = cluster of differentiation; βTCP = beta-tricalcium phosphate; CFU = colony forming units; ml = milliliters; BA = bone area; OPN = osteopontin; PRP = platelet-rich plasma; mg = milligrams; PCL-DCB = polycaprolactone-decellularized bovine bone extracellular matrix; BV = bone volume; VA = vascular area; PLA = polylactic acid; DBM = demineralized bone matrix; SD = Sprague-Dawley; BVF = bone volume fraction; Tb.Th = trabecular thickness; PLGA = poly(lactide-co-glycolide); NZW = New Zealand White; BMD = bone mineral density; Tb.Sp = trabecular separation; PMN = polymorphonuclear; ONJ = osteonecrosis of the jaw; pz = patients; BCP = biphasic calcium phosphate; OV/TV = osteoid volume/tissue volume; GAG = glycosaminoglycans; kg = kilograms; SB = subchondral bone; OA = osteoarthritis; kDa = kilodaltons; SDF = stromal cell-derived factor; PBS = phosphate-buffered solution; NOD/SCID = nonobese diabetic/severe combined immunodeficiency; JKOM score = Japanese Knee Osteoarthritis Measure; VAS score = visual analog scale score; WOMAC score = the Western Ontario and McMaster Universities Osteoarthritis score; SF = synovial fluid; KOOS score = Knee Injury and Osteoarthritis Outcome Score; ADL = Activities of Daily Living; QOL = quality of life; BM = bone marrow; ROM = range of motion; MOCART = magnetic resonance observation of cartilage repair tissue; MSCs = mesenchymal stem cells; AOFAS score = American Orthopedic Foot and Ankle Score; IKDC = International Knee Documentation Committee; EQ-VAS = EuroQol-visual analog scale; CT = cartilage thickness; DDFT = deep digital flexor tendon; no. = number; FG = fibrin glue; SNQ = signal-to-noise quotient; BMP = bone morphogenetic protein; NIAT = noninsertional Achilles tendinopathy; PD = peri- and intratendinous flow; MR-Si = MR signal intensity; VISA-A score = Victorian Institute of Sports Assessment—Achilles questionnaire; SF-36 = Short Form 36 Health Survey; AECs = amniotic endothelial cells; hAECs = human amniotic endothelial cells; NRF2 = nuclear factor erythroid 2-related factor 2; KEAP1 = Kelch-like ECH-associated protein 1; PEMF = pulsed electromagnetic field; Hz = Hertz; min = minutes; hFOB = human fetal osteoblastic; TGFβ1 = transforming growth factor β1; μg = micrograms; VEGF = vascular endothelial growth factor; oAECs = ovine AECs; CaP = calcium phosphate; Tb.N = trabecular number; hAFMSCs = human amniotic fluid mesenchymal stem cells; hAMSCs = human amniotic membrane mesenchymal stem cells; HAM = human amniotic membrane; ICRS score = International Cartilage Repair Society; PG = polygalacturonase; TNMD = tenomodulin; SCXB = scleraxis; TEA = telomere area; TEF = feret maximum; MEAND = mean densitometric value; SDFT = superficial digital flexor tendon; FDST = flexor digitorum superficialis tendon.