Wharton’s jelly-derived mesenchymal stem cells (WJ-MSCs) are emerging as a promising source for bone regeneration in the treatment of bone defects. Previous studies have reported the ability of WJ-MSCs to be induced into the osteogenic lineage. The purpose of this review was to systematically assess the potential of WJ-MSC differentiation into the osteogenic lineage. A comprehensive search was conducted in Medline via Ebscohost and Scopus, where relevant studies published between 1961 and 2018 were selected. The main inclusion criteria were that articles must be primary studies published in English evaluating osteogenic induction of WJ-MSCs. The literature search identified 92 related articles, but only 18 articles met the inclusion criteria. These include two animal studies, three articles containing both
About 25 years ago, the umbilical cord was considered to be a type of medical waste, until it was found to be a rich source of stem cells [
Anatomical compartment of Wharton’s jelly mesenchymal stem cell.
It has been reported that WJ also contains myofibroblast-like stromal cells, collagen fibers, proteoglycans, fibroblasts, and macrophages. WJ has garnered interest due to its availability, the noninvasive method of collection, and high cell yields. It has been demonstrated that mesenchymal stem cells (MSCs) isolated from the umbilical cord express matrix receptors (CD44 and CD105) and integrins (CD29 and CD51), but not hematopoietic lineage markers (CD34 and CD45) [
WJ, also known as
Cui and colleagues have successfully improved cognitive function in a mouse model of Alzheimer’s disease using intravenously delivered WJ-MSCs, which reduced oxidative stress and promoted hippocampal neurogenesis [
WJ harbours MSCs that possess a similar phenotype as harvested from the bone marrow and other sources. WJ-MSCs do not express HLA-DR and costimulatory molecules CD40, CD80, and CD86 which are essential for the activation of T-cells [
It is documented that BM-MSCs harbour viruses, which is a major drawback in clinical application. There are reports from patients who undergo BM-MSC transplant who are infected with viral infection as a complication of the cell-based therapy [
Generally, MSCs are known to migrate towards the injury site and help the healing process. The migration process, known as homing, is defined as the arrest of MSCs within the vasculature of a tissue before it crosses over the endothelium [
In a study conducted by Granero-Moltó et al., MSCs are migrated to the fracture site via the CXCR4 receptor causing improvement of biomechanical properties and increasing the cartilage and bone of the callus [
Bone repair or bone regeneration is characterized by a series of tissue transformation mechanisms including resorption and formation of hard and soft tissue. Therefore, mineralized tissue remodelling is required for the involvement of various cell types including osteoclast and osteoblast. Osteoblasts are bone-forming cells that can be found at the surface of bone, while osteoclasts are multinucleated bone-resorbing cells derived from bone marrow stem cells [
Bone remodelling consists of five consecutive phases: (1) the resorption phase, where osteoclasts break down the bone tissue, resulting in mineral release; (2) the reversal phase, where mononuclear cells appear on the bone surface; (3) the formation phase, where osteoblasts trapped in the bone matrix become osteocytes; (4) the mineralization phase, where osteocytes produce type I collagen and other substances that make up the bone extracellular matrix; and (5) the termination phase [
Mechanism of bone regeneration and activation of signaling pathways.
The differentiation of MSCs depends on which signalling pathway is activated. Apart from osteoblasts, WJ-MSCs have also been demonstrated to differentiate into other mesenchymal cell lineages such as hepatocytes [
In osteoblasts, lineage-specific gene expression control by specific transcription factors, i.e., Cbfa-1/RUNX2, acts to regulate osteoblastic specific gene expression [
The expression of transcription factors is controlled by several pathways that are activated by growth factors (GFs) that bind to a specific receptor. These growth factors include fibroblast growth factor (FGF), transforming growth factor-
Albeit many have used WJ-MSCs in the studies, the safety and efficacy of its application are indecisive particularly in bone regeneration. There are several aspects that need to be considered prior to using WJ-MSCs that may influence the yield and its stemness potency. Different parts of the umbilical cord generated diverse frequencies of MSCs and cell populations [
The current standard commonly used for bone tissue replacement is bone grafting obtained from patients themselves (autograft) or from other individuals (allograft). However, this has raised various effects including immunoreactivity and infection as well as procedure. WJ-MSCs have proved its capability to help in bone regeneration for clinical application. Qu et al. treated 36 patients with nonunion bone fracture with WJ-MSCs cultured with platelet-rich plasma (PRP) resulting in a faster recovery with no infection recorded compared to the other 36 patients with autoiliac treatment [
To this date, there are many various positive outcomes upon WJ-MSC treatment in clinical trials for different disorders including neurology [
A systematic review was conducted to systematically assess articles on the potential of WJ-MSCs for bone regeneration. Two databases were comprehensively used to search for relevant studies, i.e., Medline via Ebscohost and Scopus. For search term keywords, the combination of words used was “Wharton’s jelly” AND “osteo
The year limit for searches was from 1961 to 2018, and only studies published in English were considered. The search outcomes identified all articles containing the words Wharton’s jelly, umbilical cord, osteogenesis, osteogenic, and bone. Databases were searched individually to ensure all relevant studies were considered. The titles and abstracts were carefully screened for eligibility related to the topic of interest. Primary studies related to bone formation or bone regeneration were included. Review articles, news articles, letters, editorials, and case studies were excluded from the search.
Data were extracted from each eligible article by two reviewers. The selected papers were screened in several phases prior to inclusion. First, the titles that were not relevant to the topic were excluded. Next, the abstracts of the papers were screened, and unrelated studies were excluded. All duplicates were removed. The following data were summarized from the selected studies: (1) authors, (2) type of study, (3) subject/sample, (4) induction factor, (5) methodology, (6) results, and (7) conclusions.
The primary searches identified 386 articles: 41 articles came from Medline and 345 articles were found in Scopus. To minimize bias and improve the strength of the related articles, two reviewers independently assessed the articles according to the inclusion and exclusion criteria. There were 244 articles removed as they were unrelated to either Wharton’s jelly or osteogenesis/bone. A joint discussion was conducted to achieve consensus where differences emerged during the assessment. From the 142 remaining articles, 50 duplicates were removed before full articles were retrieved. From 92 articles, 74 articles were rejected based on the inclusion criteria as the articles were not primary studies, were not related to Wharton’s jelly or osteogenesis, or were not available as full articles. Finally, a total of 18 studies were selected for data extraction in this review. The flow chart of the selection process is shown in Figure
Flow chart of the article selection process using the Scopus and MEDLINE databases.
All studies were published between 1961 and 2018. An article reported on animal studies (in vivo), two articles on both
Summary and classification of the 18 articles selected from the database search.
No. | Author and year | Type of study | Subject/sample | Induction factor | WJ-MSC isolation method | Results | Conclusion |
---|---|---|---|---|---|---|---|
1. | Fu et al. 2018 [ |
(i) Human umbilical cord-derived mesenchymal stem cells (UC-MSCs) |
Differentiation medium |
(i) Enzymatic digestion |
(1) MicroCT result showed that transplantation of UC-MSCs increased bone mass in the distal condyle of normal rat femur compared to other groups |
UC-MSCs able to be differentiated into osteoblast and are safe for transplantation in bone disease treatment. | |
Osteoclast differentiation | |||||||
2. | Al Jofi et al. 2018 [ |
(i) Wharton’s jelly mesenchymal stem cells (WJ-MSCs) | (i) 10 |
(i) Commercial UC-MSCs |
Metformin-treated UC-MSCs increased in mineralization stained through Alizarin Red Staining. But in OCT-1- (organic cation transporter-) siRNA-transfected cells, a significant decrease in calcium-rich nodule formation was observed. | OCT-expressing WJ-MSCs have the ability to be differentiated into osteoblasts when induced with metformin. | |
3. | Bharti et al. (2018) [ |
(i) Wharton’s jelly mesenchymal stem cells (WJ-MSCs) | (i) Osteogenic medium |
(i) Explant method |
(1) Bone nodules: formed by cells from all segments |
WJ-MSCs are a good cell source for autologous/allogeneic stem cell source. | |
4. | Batsali et al. 2017 [ |
(i) Bone marrow mesenchymal stem cell (BM-MSCs) |
Differentiation medium: |
(i) Explant method |
(1) Osteogenic differentiation (Alizarin Red and von Kossa staining): WJ-MSCs showed similar staining potential as BM-MSC |
The osteogenic differentiation potential of WJ-MSCs is regulated by WISP1 and sFRP4, respectively. | |
5. | Zajdel et al. 2017 [ |
(i) Adipose tissue (AT-MSCs) |
Osteogenic medium (Lonza): |
(i) Commercial AT-MSCs and UC-MSCs |
(1) Calcium deposition by Alizarin Red staining |
WJ-MSCs have the ability to differentiate into the osteogenic lineage. | |
6. | Mechiche Alami et al. 2017 [ |
(i) WJ-MSCs | Calcium phosphate (CaP) substrate build-up (without osteogenic induction | (i) Commercial UC-MSCs |
(1) Gene expression analysis |
Excellent osteogenic potential of sprayed CaP and WJ-MSCs in bone tissue engineering | |
7. | Szepesi et al. 2016 [ |
(i) WJ-MSCs |
Differentiation medium: |
(i) Enzymatic digestion UC-MSCs |
(1) Osteogenic differentiation: AT-MSCs and PDL-MSCs showed greater calcium deposition |
WJ-MSCs have osteogenic potential and are good cell sources for bone regeneration. | |
8. | Lim et al. 2016 [ |
Human WJ-MSCs |
(i) Osteogenic medium |
(i) Enzymatic digestion |
Bone nodules: formed by cells from all segments | WJ-MSCs are a good cell source for bone regeneration. | |
9. | Kargozar et al. 2018 [ |
(i) BM-MSCs |
(i) Nanocomposite scaffolds (3D bioactive glass/gelatin scaffolds (BaG/Gel) consisting of SiO2-P2O5-CaO (64% SiO2, 5% P2O5, and 31% CaO). | (i) Enzymatic digestion |
BM-MSCs, grown on BaG/Gel nanocomposite scaffolds, are possible sources for bone regeneration. | ||
10. | Todeschi et al. 2015 [ |
(i) UC-MSCs |
(i) Ceramic scaffolds (Skelite; 4 × 4 × 4 mm cubes of 33% hydroxyapatite and 67% silicon-stabilized tricalcium phosphate, Si-TCP) |
(i) Explant method |
(1) Histological assessment revealed the formation an immature bone-like structures and compact fibrous tissue in UC-MSC-seeded constructs |
UC-MSCs promote bone regeneration. | |
11. | Karadas et al. 2014 [ |
(i) WJ-MSCs |
(i) Collagen scaffolds with |
(i) Explant method |
(1) Cell proliferation assays: |
Collagen foam with the use of CaP crystals formed | |
von Kossa staining: | |||||||
12. | Ramesh et al. 2014 [ |
(i) WJ-MSCs | (i) Hydrogel alginate microspheres |
(i) Explant method |
(1) Characterization of osteodifferentiated WJ-MSCs via: |
WJ-MSCs encapsulated in hydrogel alginate microspheres have osteogenic potential for stem cell-based tissue engineering. | |
13. | Baba et al. 2012 [ |
Human umbilical cord mesenchymal stem cells (hUC-MSCs) | Differentiation medium: |
(i) Enzymatic digestion |
(3) Osteogenic differentiation: strong calcium deposition |
UC-MSCs supplemented with growth factors and serum have osteogenic differentiation potential for bone regeneration. | |
14. | Penolazzi et al. 2012 [ |
(i) WJ-MSCs | (i) Porcine urinary bladder matrix (pUBM) | (i) Enzymatic digestion |
(1) Proliferation assays showed |
The combination of WJ-MSCs and pUBM shows the promise of scaffolds for bone regeneration. | |
15. | Wang et al. 2011 [ |
(i) UC-MSCs | (i) Poly-L-lactic acid (PLLA) scaffold |
(i) Enzymatic digestion |
(1) Biochemical assays were performed to assess |
WJ-MSCs are a suitable cell source for a sandwich approach strategy in osteochondral tissue engineering. | |
16. | Schneider et al. 2010 [ |
Human mesenchymal stem cells (hMSC): |
(i) Scaffold: 3D collagen gel |
(i) Enzymatic digestion |
(1) Scaffold: |
UC-MSCs have a significant therapeutic impact in bone tissue engineering in the future. | |
17. | Hsieh et al. 2010 [ |
(i) |
(i) WJ-MSCs |
Osteogenic differentiation medium: |
(i) Enzymatic digestion |
(1) Array data showed that both BM-MSCs and WJ-MSCs expressed multilineage differentiation properties. |
WJ-MSCs are capable of differentiating into the osteogenic lineage, but BM-MSCs are superior. |
18. | Hou et al. 2009 [ |
(i) |
(i) hUC-MSCs |
(i) BMP-2 treatment: |
(i) Enzymatic digestion |
(1) Trilineage differentiation |
BMP2-induced UC-MSCs have good osteogenic differentiation (indicated by the activation of BMP2 signaling) and may be used in tissue-engineered bone. |
The database search provided 18 articles related to Wharton’s jelly, umbilical cord, osteogenesis, osteogenic lineage, and bone. From these articles, various tissue sources were assessed for potential MSCs. Each of these sources was examined regarding MSC differentiation capacities into the adipogenic, chondrogenic, and osteogenic lineages. This review assessed the osteogenic potential of WJ-MSCs, which may have remarkable potential for bone regeneration in the clinic.
Mesenchymal stem cells (MSCs) have attracted attention because of their unique plasticity and ability to differentiate into multiple cell lineages, i.e., osteoblasts, chondrocytes, and adipocytes, with potential for clinical usage. The bone marrow is a primary source of MSCs. However, it has been reported that the frequency as well as the differentiation potential of BM-derived MSCs (BM-MSCs) decline with increasing age [
It is important to characterize cells derived from tissues to determine the type of cell population that exists in the preparation. A heterogeneous population could influence the differentiation properties, specifically the osteogenic potential of MSCs for bone regeneration. There are a few surface markers that are commonly reported for MSCs such as CD13, CD29, CD44, CD73, CD90, CD105, and CD166. MSCs do not express CD31, CD144, and CD309 (endothelial cell markers) or CD14, CD34, CD45, CD117, and CD133 (hematopoietic cell markers) [
WJ-MSCs have been shown to have good potential for osteogenic differentiation. These cells display all features of functional osteocytes/osteoblasts based on osteogenic gene expression, extracellular matrix (ECM) mineralization, and the ability to adhere to a fabricated scaffold [
Seven studies out of 18 selected articles used chemical factors to promote osteogenesis in WJ-MSCs. Batsali et al. [
It is noteworthy that the microenvironment influences cell behaviour and leads to the production of a specific chemical composition that builds the ECM. Therefore, fabricated scaffolds have been actively investigated to find better materials and to produce the best structure of ECM-like components. From the database search, eight out of 18 articles investigated the fabrication of various scaffolds to test the potential of WJ-MSCs to promote complex bone regeneration. Various biomaterials were used to construct these scaffolds, ranging from collagen hydrogels [
The first phase in scaffold development used collagen as the main organic component in bone tissue for bone grafting [
Scaffold design then moved to the second phase, in which bioactive glass has been used as a scaffold in bone tissue engineering [
WJ-MSCs were first isolated by Mitchell et al. in 2003. During embryogenesis, totipotent cells such as primordial germ cells and hematopoietic stem cells migrate from the yolk sac through this region to populate target tissues in the embryo and fetus [
The authors declare that they have no conflicts of interest.
The research was carried out with the financial support of Universiti Kebangsaan Malaysia and AMRUS Medik Sdn. Bhd. through research grant numbers FF-2017-482 and FF-2017-020, respectively.