## 1 Introduction
These considerations can be summarized as follows: (1) the choice between the use of autologous or allogeneic cells, (2) the availability of the desired tissue for cells and subsequent harvesting procedure, (3) donor site morbidity, (4) the efficiency of the cell isolation procedure and final yield of harvested cells, (5) the osteogenic and angiogenic potential of cells, (6) the proliferation rate of cells, (7) the homogeneity of the isolated cells, (8) the phenotype stability and cell safety after implantation, (9) the possibility of immunogenicity, and (10) the development of quality control measures for the generation of cells and grafts [24]. Prior to the use of in vivo experiments, the harvested cells are usually expanded in tissue culture treated (TC-treated) dishes under appropriate cell culture conditions. This work results in a significant increase in the number of cells desired, which may be useful for selection and their enrichment [25] (Figure 1). In the present study, we have reviewed and summarized a large number of previously reported studies in which different somatic and stem cells (Table 1) were used for bone tissue engineering (BTE) strategies both in vitro and in vivo. For this aim, we collected the relevant articles from the databases of Scopus, Web of Science (ISI), and PubMed. In addition, we present and discuss the general information of mammalian cells including their history, isolation procedures, properties, advantages, and disadvantages regarding BTE. The focus of the present study is to show the usability of each cell type for bone reconstructive strategies and their pros and cons based on the evidence of the comparison in vitro and in vivo osteogenic potential. The conclusion on choosing the best cell source as an ideal candidate for bone tissue repair and regeneration is tough because of the various conditions applied in experiments. \begin{table}
\begin{tabular}{c c c c} \hline \hline
**Cell Type** & & **Advantages** & **Disadvantages** \\ \hline \multirow{4}{*}{Autologous osteoblasts} & - & Lack of immune rejection & - & Need for ex vivo expansion \\  & - & Low cost & (a time-consuming procedure) \\  & - & No requirement for cell & - & May be harmful \\  & - & Ability to differentiate into cells of all & - & Ethical issues \\  & - & three primary germ layers (ectoderm, & - & The risk of tumorigenicity \\  & - & mesoderm, and endoderm) & - & Difficult culturing \\  & - & Immortality & - & Maybe immunogenic \\ \hline \multirow{4}{*}{Fetal stem cells (AFSCs, & - & High proliferation rate & - & Inability to differentiate into the cells of three germ layers \\  & - & Lack of ethical issues & - & Lower potential regarding \\  & - & Lack of tumorigenicity * & & osteogenic differentiation \\  & - & Immuno-privileged properties & & than other cells \\ \hline \multirow{4}{*}{Huduced pluripotent stem cells (BM-MSCs, & - & Ease availability & - & The limited lifespan \\  & - & Lack of ethical issues & & in vitro condition \\  & - & Lack of tumorigenicity * & - & Inability to differentiate into \\  & - & Immuno-privileged properties & & the cells of three germ layers \\ \hline \multirow{4}{*}{H. The cell niche within the bone tissue. Osteoblasts, osteocytes, osteoclasts, mesenchymal cells, and endothelial cells of blood vessels create the niches and contribute to the maintenance and differentiation of hematopoietic stem cells (HSCs). With permission from Reference [26].} \\  & & & \\ \end{tabular}
\end{table} 
Table 1: Overview of the somatic and stem cells used in BTE applications. Figure 1: The cell niche within the bone tissue. Osteoblasts, osteocytes, osteoclasts, mesenchymal cells, and endothelial cells of blood vessels create the niches and contribute to the maintenance and differentiation of hematopoietic stem cells (HSCs). With permission from Reference [26].