Dr Soon Koo Baik from the Yonsei University Wonju College of Medicine, and Dr. Si Hyun Bae from The Catholic University of Korea and their colleagues have conducted an important phase 2 clinical trial that tests the ability of mesenchymal stem cells from bone marrow to treat cirrhosis of the liver. In this trial, seventy-two patients who had established cirrhosis of the liver participated in a multicenter, randomized, open-label, phase 2 trial (published in the journal Hepatology, DOI:10.1002/hep.28693).
The liver is a hugely important organ. Not only is it the largest internal organ in our bodies, but it serves as the main metabolic factory of the body because of the outsized role it plays in metabolism. The liver takes up and stores and processes nutrients from food. Once it processes fats, sugars, and amino acids, the liver delivers them to the rest of the body. The liver also makes new proteins, such as clotting and immune factors, produces bile, which helps the body absorb fats, cholesterol, and fat-soluble vitamins, and removes waste products the kidneys cannot remove, such as fats, cholesterol, toxins, and medications.
The condition known as cirrhosis is a condition in which the liver gradually deteriorates and becomes unable to function normally due to chronic, or long-lasting, injury. The accumulation of scar tissue in the liver is typically slow and gradual and as scar tissue replaces more healthy liver tissue, the liver begins to fail. Scar tissue also partially blocks the flow of blood through the liver. Chronic liver failure (also known as end-stage liver disease) culminates in the inability of the liver to perform important functions. Since the liver is an organ that have a good deal of regenerative ability, end-stage liver disease essentially becomes so damaged that it cannot effectively replace damaged cells.
Cirrhosis is most commonly called by chronic alcoholism, but so can chronic viral infections by viruses like hepatitis B virus and hepatitis C virus. Additionally, particular genetic diseases can also cause cirrhosis in children or young adults.
Mesenchymal stem cells have the ability to secrete cocktails of pro-healing molecules that might be able to support the growth and survival of liver cells. A variety of experiments in animals have established that the administration of mesenchymal stem cells (MSCs) from bone marrow (Truong, NH, et al., Stem Cells Int. 2016;2016:5720413. doi: 10.1155/2016/5720413; Almeida-Porada G, et al., Exp Hematol. 2010;38:574–580; Berardis S, et al., World J Gastroenterol. 2015;21:742–758), and other sources (De Ugarte DA, et al., Cells Tissues Organs. 2003;174:101–109; in ‘t Anker PS, etr al., Haematologica. 2003;88:845–852; Lee OK, et al., Blood. 2004;103:1669–1675) can decrease inflammation within the liver, inhibit the death of liver cells and promote their survival, and promote the regeneration of residential liver cells.
In clinical trials, administration of MSCs to cirrhosis patients has established the safety of MSC-based treatments (Amin MA, et al., Clin Transplant. 2013;27:607–612; El-Ansary M, et al., Stem Cell Rev. 2012;8:972–981; Jang YO, et al., Liver Int. 2014;34:33–41; Kharaziha P, et al., Eur J Gastroenterol Hepatol. 2009;21:1199–1205; Mohamadnejad M, et al., Arch Iran Med. 2007;10:459–466). Unfortunately, the design of these trials involved the mixing of patients with alcohol-based cirrhosis, viral-based cirrhosis, and other types of cirrhosis. Therefore, it is impossible to draw any conclusions about the efficacy of MSC transplantations on the basis of these trials. However, one trial, by Jang, et al, examined the effect of MSCs from bone marrow in patients with alcoholic cirrhosis. After 11 patients received MSC implantations, improvements in liver tissue architecture were observed in 6/11 patients, and 10 patients showed recovery of liver function. These 10 patients had decreased expression of molecules that induce scarring in the liver (i.e. TGF-β1, collagen type I, and α-smooth muscle actin). Significantly, Jang and others observed these improvements in the absence of significant complications or side effects during the study period. On the strength of these results, a larger phase 2 study is certainly warranted (see F. Ezquer, et al., World J Gastroenterol. 2016 Jan 7; 22(1): 24–36).
In this Bak and Bae clinical trials, 72 patients were randomly assigned to three groups that consisted of a control group and two autologous bone marrow-based MSC groups that underwent either one-time or two-time hepatic arterial injections of 5 × 10 MSCs, 30 days after bone marrow aspiration. All patients also underwent a follow-up biopsy 6 months after enrollment and adverse events were monitored for 12 months.
The primary endpoint in this study was the improvement in the amount of scar tissue in biopsies (as assayed by Picrosirius-red staining). The secondary endpoints included liver function tests, a measure of the severity of cirrhosis called the Child-Pugh score, and another score called the Model for End-stage Liver Disease (MELD) score. The outcomes were analyzed by per-protocol analysis.
When it comes to the amount of scar tissue in the patient’s livers, patients that received one-time and two-time bone marrow-based MSC administrations, showed 25% (19.5±9.5% vs. 14.5±7.1%) and 37% (21.1±8.9% vs. 13.2±6.7%) reductions in the amount of liver scar after MSC administration, respectively (P0.05). The Child-Pugh scores of both BM-MSC groups (one-time: 7.6±1.0 vs. 6.3±1.3 and two-time: 7.8±1.2 vs. 6.8±1.6) were also significantly improved following BM-MSC transplantation (P<0.05) compared to the control group that did not receive MSCs. Most significantly, perhaps, is that the proportion of patients with adverse events did not differ among the three groups.
From this larger phase 2 study, it seems that transplantation of a patient’s own bone marrow-based MSCs can safely improve the degree of scarring in the liver of cirrhosis patients and also improve liver function in patients with alcoholic cirrhosis. This study seems to confirm what was observed in preclinical studies in laboratory animals and extends what was observed in the phase 1 studies. While more work is certainly required, these results are certainly hopeful.