Use of mesenchymal stem cells to treat liver fibrosis: Current situation and future prospects

Table 1 Preclinical and clinical studies representing the development of anti-fibrotic strategies

Antifibrotic drug		Preclinical/clinical results	Disease model	Ref.
Downregulation of hepatic stellate cell (HSC) activation
	Peroxisomal proliferator-activated receptor gamma agonist (pioglitazone)	Inhibition of HSC activation and amelioration of hepatocyte necroinflammation in rats after 8 wk	Carbon tetrachloride (CCl4)-induced liver fibrosis	[44]
		Reduction of steatosis, but not fibrosis compared to placebo, in patients with NASH after 6 mo (26 pioglitazone; 21 placebo)	Nonalcoholic steatohepatitis (NASH)	[45]
		No benefit of pioglitazone over placebo in term of steatosis and fibrosis in patients with NASH after 96 wk (80 pioglitazone; 83 placebo)	NASH	[46]
	Interferon gamma (IFN-γ)	Inhibition of the activation of HSC and extracellular matrix production	CCl4-induced liver fibrosis	[47]
		Improvement of fibrosis scores in patients with chronic hepatitis B virus (HBV) infection after 9 mo (54 IFN-γ; 29 control)	Chronic HBV infection	[48]
	Antioxidant (vitamin E)	No reversion of fibrosis in patients with advanced liver disease after 1 yr (IFN-γ1b 100 μg 169; IFN-γ1b 200 μg 157; placebo 162)	Chronic hepatitis C virus (HCV) infection	[49]
		Protective effects against liver damage and cirrhosis in rats	CCl4-induced liver fibrosis	[50]
		No benefit on liver function tests in patients with mild to moderate alcoholic hepatitis after 1 yr (25 vitamin E, 26 placebo)	Alcoholic hepatitis	[51]
Neutralization of proliferative, fibrogenic and contractile responses of HSC
	Anti-transforming growth factor beta (TGF-β)	Supression of fibrosis in rats after 3 wk	Dimethylnitrosamine-induced liver fibrosis	[52]
	Short interference RNA	Inhibition of the expression of TGF-β1 and attenuation of liver fibrosis in rats	High-fat diet and CCl4-induced model of liver fibrosis	[58]
	Endothelin antagonist	Nonpeptide endothelin-A receptor antagonist, LU 135252, reduced collagen accumulation in rats after 6 wk	Secondary biliary fibrosis	[53]
	Angiotensin system inhibitor	Olmesartan, an angiotensin II type 1 receptor blocker, decreased expression of collagen genes and attenuated liver fibrosis in rats after 15 wk	Methionine-choline-deficient rat model of NASH	[54]
		Angiotensin-converting enzyme inhibitors (ACEi) and angiotensin receptor-1 blocker (ARB) did not retard the progression of liver fibrosis in patients with advanced liver fibrosis after 3.5 yr (66 ACEi/ARB, 126 non-ACEi/ARB, 343 no antihypertensive medication)	Chronic hepatitis C	[55]
	Colchicine	Colchicine and colchiceine (metabolite of colchicine) prevented the increase in collagen synthesis and increased the intracellular degradation of collagen rats	CCl4-induced liver fibrosis	[56]
		Colchicine improved fibrosis marker expression, but not histological finding, in patients with hepatic fibrosis after 12 mo (21 colchicine; 17 control)	Liver fibrosis of various etiologies	[57]
Promotion of HSC apoptosis
	Gliotoxin	Morphologic alterations typical of HSC apoptosis in vitro (activated rat and human HSCs) and reduction of the number of activated HSCs in rats	CCl4-induced liver fibrosis	[59]
	Sulfasalazine	Induction of activated HSC apoptosis, by inhibiting nuclear factor kappa B-dependent gene transcription, both in vitro (activated rat and human HSC) and in vivo	CCl4-induced liver fibrosis	[60]
Promotion of matrix degradation
	Matrix metalloproteinase (MMP) inducer	Urokinase-type plasminogen activator, an initiator of the matrix proteolysis cascade, induced collagenase expression and reversal of fibrosis rats	CCl4-induced liver fibrosis	[61]
	Tissue inhibitor of matrix metalloproteinase (TIMP) inhibitor	Polaprezinc, a zinc-carnosine chelate compound, attenuated fibrosis by inhibiting TIMP expression during a later phase, thus promoting fibrinolysis, in mice after 10 wk	Dietary methionine and choline deficient (MCD)-induced NASH	[62]
Reduce inflammation
	Interleukin 10	Inhibition of HSC activation and decrease of the expression of TGF-β1, MMP-2, and TIMP-1 in rats	CCl4-induced liver fibrosis	[63]
		Anti-inflammatory effect, but increased HCV viral burden via alterations in immunologic viral surveillance, in patients (30 subjects for 3-dose trial)	Chronic hepatitis C	[64]
	Anti-tumour necrosis factor-α	Infliximab decreased necrosis, inflammation, and fibrosis in rats	Dietary MCD-induced NASH	[65]
		Infliximab improved Maddrey’s score in patients after 28 d (20 subjects)	Alcoholic hepatitis	[66]
	Ursodeoxycholic acid (UDCA)	Reversion of liver damage in rats	CCl4-induced liver fibrosis	[67]
		Reduction of periportal necroinflammation and, if initiated at the earlier stages I-II of the disease, delay of the progression of histologic stage in patients after 2 yr (200 UDCA, 167 placebo)	Primary biliary cirrhosis	[68]
Inhibition of collagen I cross-linking
	Anti-Lysyl oxidase-like-2	Reduction of liver fibrosis, decrease in the number of myofibroblasts and lower p-Smad3 signal	CCl4-induced liver fibrosis	[69]

Table 2 In vivo studies using mesenchymal stem cells to treat liver fibrosis

Species	Fibrosis induction	Administration route	MSC source	Number of cells injected/ animal	Results	Anti-fibrotic mechanisms proposed	Ref.
Rats	CCl4 IP	Tail vein	Human umbilical cord blood	1 × 106	Liver fibrosis alleviated 4 wk post-infusion Improvement of liver function	Differentiation into hepatocyte-like cells	[127]
Rats	CCl4 IP	Portal vein	Rat adipose tissue	2 × 106	Improvement of liver functional tests, histological findings and microcirculation 6 wk post-infusion	Not mentioned	[128]
Mice	CCl4 IP	Intrahepatic	Murine bone marrow	1 × 106	Reduced fibrosis and apoptosis 30 d post-infusion Improvement of liver function	Not mentioned	[129]
Mice	CCl4 IP	Tail vein	Murine bone marrow	1 × 106	Thinner fibrotic areas and decreased collagen depositions 4 wk post-infusion Improvement of liver function	Promotion of hepatocyte proliferation and modulation of inflammation	[130]
Rats	CCl4 SC	Portal vein	Human bone marrow	1 × 106	Reduced fibrosis 4 wk post-infusion Improvement of liver function	Differentiation into hepatocyte-like cells expression of MMPs by MSCs	[131]
Mice	CCl4 IP	Tail vein	Murine bone marrow	1 × 106	Decrease in liver fibrosis 4 wk after transplantation	Increased expression of MMPs	[132]
Rats	CCl4 SC/DMN IP	Intraveinous	Rat bone marrow	3 × 106	Decrease in collagen deposition and of α-SMA expression Improvement of liver function	Not mentioned	[133]
Rats	CCl4 SC	Tail vein	Rat bone marrow	3 × 106	Decrease in collagen deposition Elevation of serum albumin	Not mentioned	[134]
Mice	CCl4 IP	Tail vein	Human bone marrow	5 × 105	Reduction in fibrosis 4 wk after cell infusion	Enhanced expression of MMP-9 and decreased expression of α-SMA, TNFα and TGFβ	[135]

MSC: Mesenchymal stem cell; DMN: Dimethylnitrosamine; MMP: Matrix metalloproteinase; α-SMA: Alpha-smooth muscle actin; TNFα: Tumour necrosis factor-α; TGFβ: Transforming growth factor beta.

Table 3 Clinical trials using mesenchymal stem cell to treat liver fibrosis

Cell source	Administration route	Number of cells infused	Patient population	Number of patients	Follow up period	Endpoints	Efficacy	Ref.
Umbilical cord	Intravenous	5 × 105/kg, 3 times	Chronic hepatitis B	30 treatment 15 control	1 yr	Safety/efficacy	Improvement of liver function and MELD score Reduced acites	[144]
Umbilical cord	Intravenous	5 × 105/kg, 3 times	Chronic hepatitis B	24 treatment 19 control	48 or 72 wk	Safety/efficacy	Improvement of liver function and MELD score Increased survival rates	[145]
Umbilical cord	Intravenous	5 × 105/kg, 3 times	Primary biliary cirrhosis	7	48 wk	Safety/efficacy	Decrease in serum alkaline phosphatase and γ-glutamyltransferase levels Alleviation of fatigue and pruritus Decrease of ascites	[146]
Bone marrow (autologous)	Intravenous	30 × 106/patient	3 cryptogenic 1 autoimmune hepatitis	4	1 yr	Safety/efficacy	Improvement of MELD score	[147]
Bone marrow (autologous)	Intravenous (peripheral vein or portal vein)	30 × 106-50 × 106/patient	4 chronic hepatitis B 1 chronic hepatitis C 1 alcoholic cirrhosis 2 cryptogenic	8	24 wk	Safety/efficacy	Improvement of liver function and MELD score	[148]
Bone marrow (autologous)	Hepatic artery	3,4 × 108/patient	Chronic hepatitis B	53 treatment 105 control	192 wk	Safety/efficacy	Improvement of Alb, TBIL, PT and MELD score	[149]
Bone marrow (autologous)	Intravenous	1 × 106/kg	Chronic hepatitis C	15 treatment 10 control	6 mo	Efficacy	Improvement of liver function and MELD score	[150]
Bone marrow (autologous)	Intrasplenic	10 × 106/patient	Chronic hepatitis C	20	6 mo	Safety/efficacy	Decrease od TBIL, AST, ALT, PT and INR Increase of the albumin levels	[151]
Bone marrow (autologous)	Hepatic artery	5 × 107/patient, twice	Alcoholic cirrhosis	12	12 wk	Efficacy	Histological improvements Improvement of Child-Pugh score Decrease of TGF-β1, collagen type 1 and α-SMA	[152]

MELD: Model for end-stage liver disease; Alb: Albumin; TBIL: Total bilirubin; PT: Prothrombin time; TGF-β: Transforming growth factor beta; α-SMA: Alpha-smooth muscle actin; AST: Aspartate aminotransferase; ALT: Alanine aminotransferase; INR: International normalised ratio.