Copper Content in Lumbar Vertebrae across Age Groups

Research Article

Austin J Anat. 2023; 10(1): 1111.

Copper Content in Lumbar Vertebrae across Age Groups

Mavrych V¹*; Bolgova O¹; Shypilova I²; Eryomin A³

¹Department of Anatomy and Genetics, COM Alfaisal University, Saudi Arabia

²Biochemistry Department, SOM St. Matthews University, Cayman Islands

³Anatomy Department, Luhansk State Medical University, Ukraine

*Corresponding author: Mavrych V Department of Anatomy and Genetics, COM Alfaisal University, P.O. Box 50927, Riyadh 11533, Saudi Arabia Riyadh, Saudi Arabia. Tel: +966 11 215 7629 Email: [email protected]

Received: June 14, 2023 Accepted: July 14, 2023 Published: July 21, 2023


Copper, an essential trace element in bone tissue, plays a crucial role in the active centers of vital enzymes. It is involved in the synthesis of key connective tissue proteins like collagen and elastin, which form the structural matrix of bones and cartilage. This research aims to investigate the copper content in human lumbar vertebrae and explore how it changes with age, with a particular focus on gender differences. The study involved the analysis of the third lumbar vertebrae from 211 individuals spanning ages 0 to 90 years. Copper content was determined using an atomic absorption spectrophotometer C-115M1 (PA “Electron,” Ukraine), while the organic component of bone tissue was calculated using the weighing method. The obtained data were statistically analyzed using ANOVA and independent samples t-tests. The results revealed that copper levels in the spongy bone of human lumbar vertebrae ranged from 2.45 to 6.12 mg/kg dw, and the organic component of bone tissue varied from 6.5% to 49.6%. The statistical analysis demonstrated a positive correlation between the organic component and copper content in the spongy bone tissue for both males (r=0.5195, p<0.01, n=106) and females (r=0.6101, p<0.01, n=105). Our study demonstrated that bone copper levels decrease with age, irrespective of gender. A strong positive correlation was observed between bone copper and organic content in the spongy bone of human lumbar vertebrae.

Keywords: Lumbar vertebra; Copper; Bone composition; Trace elements


Bone is a calcified tissue that responds to changes in dietary intake and nutritional status. It consists of approximately 60% inorganic components (hydroxyapatite), 10% water, and 30% organic components (proteins). The primary functions of bone are to provide mechanical support for movement, protect vital internal organs, and regulate mineral balance within the body. In addition to well-known macro minerals, trace elements such as iron, zinc, copper, and selenium also play a role in bone metabolism [1].

The bone tissue undergoes a constant turnover process involving resorption by osteoclasts and formation by osteoblasts. The overall balance of bone depends on the relative contribution of these processes. Trace elements can influence skeletal metabolism and tissue properties indirectly by regulating macromineral metabolism or directly by affecting the proliferation or activity of osteoblasts and osteoclasts, which are incorporated into the bone mineral matrix [1].

Deficiency in trace elements can hinder the increase of bone mass during childhood and adolescence and accelerate bone loss after menopause or in old age. Deterioration in bone quality increases the risk of fractures. To identify and treat individuals at risk of non-traumatic fractures, it is important to monitor the homeostasis of trace elements, measure bone density, and assess biochemical markers of bone metabolism [2].

Within the human body, copper content ranges from 50 to 120 mg, with about two-thirds of the total copper found in the muscles and skeleton [3,4]. Copper plays a crucial role in the formation of enzymes that facilitate electron transfer and the reduction of molecular oxygen, making it essential for cellular energy metabolism [5,6]. One of these enzymes, lysyl oxidase, utilizes lysine and hydroxylysine as substrates to produce cross-links necessary for the development of connective tissues, including those in bones [6-8].

Numerous in vitro studies have confirmed the beneficial impact of copper on the cells involved in bone metabolism. Some studies demonstrated that copper ions could inhibit osteoclastic resorption [9], while other researchers have shown that the effects of copper are dependent on its dosage. Specifically, low concentrations of copper have been found to enhance the viability and growth of osteoblastic cells, whereas higher concentrations can be cytotoxic [10].

Under normal physiological conditions, copper ions can create a hypoxic microenvironment similar to hypoxia-mimicking ions and increase bone mineral density by promoting the expression of bone-related genes such as ALP, OPN, and OPN. This inhibition of active bone resorption and promotion of angiogenesis is achieved through the upregulation of vascular endothelial growth factor [11-13]. Copper has been found to downregulate the expression of Runx2 and other genes related to osteogenic differentiation, as well as inhibit collagen formation while stimulating angiogenesis in vivo studies [14]. Additionally, copper has been observed to hinder cytoskeletal changes in Bone Mesenchymal Stem Cells (BMSCs) during osteogenic differentiation, suggesting its interference with mesenchymal stem cells involved in osteogenesis by affecting cytoskeleton organization [14]. Other studies indicate that copper can also promote both osteogenesis and adipogenic differentiation of BMSCs, with a preference for the osteogenic lineage [15]. Higher concentrations of copper have been found to induce apoptosis in BMSCs [16].

In vivo, experiments on bone tissue formation have demonstrated that copper inhibits the accumulation of collagen type I and the formation of connective tissue while stimulating microvascular formation [14]. These findings suggest a balance between inhibiting collagen accumulation and promoting microvascular formation with copper supplementation, which can aid in the development of copper-containing implants to promote angiogenesis [17-19].

The insufficient amount of copper ions has detrimental effects on bone tissue, leading to increased bone resorption and disruption of lysyl oxidase [20]. Copper deficiency can result in decreased cancellous bone, weakened bone formation and mineralization, impaired cartilage integrity, and ultimately reduced bone density. Animal experiments have shown that copper deficiency leads to bone deformities, hypoplasia, fragile bones, and frequent fractures [21].

The impact of copper supplementation on bone health has been examined in several studies, primarily focusing on menopausal women. One study investigated the effects of a 3 mg copper daily intake in the diet of healthy women over a span of 2 years. The results showed decreased vertebral bone density loss compared to the control group without supplementation [22]. Another study conducted by Baker et al. explored the influence of a 3-week diet with varying levels of copper (1.6 mg/d vs. 0.7 mg/d vs. 6 mg/d) on healthy men. The transition from a copper-poor to a copper-rich diet led to a significant reduction in markers of bone resorption [23]. Thus, it can be inferred that nontoxic doses of copper are unlikely to induce detrimental changes in bone tissue.

Furthermore, another study indirectly supports the role of copper in maintaining bone integrity [24]. Cu and Zn SOD-deficient mice, which exhibited increased cytoplasmic superoxide, displayed compromised bone integrity. These mice demonstrated greater weakness in bone stiffness and decreased bone mineral density. In the lumbar vertebrae of SOD-deficient mice, there was a decrease in the presence of osteoblasts and osteoclasts on the surface area. Primary osteoblasts exhibited enhanced cell death and reduced proliferation, likely due to decreased antioxidant activity. These findings may be attributed not only to decreased collagen crosslinking but also to increased free radical production [25].

Results of studies aimed at determining the effects of excessive copper levels indicated that copper exhibits direct toxicity to cartilage and bone tissue in chicken embryos, primarily due to the inhibition of collagen synthesis [26,27], and elevated serum copper level is associated with decreased bone size and density in C57 mice [28]. Another study demonstrated that copper-induced inhibition of mineral and matrix formation remained unaffected by zinc intake [29].

In patients with Wilson's disease, copper overload can interfere with bone metabolism, resulting in a generalized loss of bone density, rickets, and abnormal osteophytes [12]. Epidemiological studies in individuals with Wilson's disease have revealed normal bone mineral density in cortical and cancellous bone but an increased risk of fractures [30]. Moreover, excessive copper levels and decreased bone strength have been associated with other conditions, such as rickets and abnormal osteophytes [31].

Excessive copper also leads to the generation of high levels of free radicals, triggering lipid peroxidation and interfering with bone metabolism, resulting in decreased bone cortex and strength. Oxidation itself can promote aging and reduce bone strength [32].

Furthermore, high concentrations of copper ions have the potential to impact collagen synthesis negatively. Ascorbic acid is well-known for its essential role in collagen production. However, at elevated levels of copper, free copper ions can reduce the half-life of ascorbic acid, leading to reduced collagen accumulation [7].

Impaired bone growth is frequently observed in various conditions linked to disrupted copper metabolism, implying a physiological significance of copper in bone tissue growth and mineralization [33]. However, recent studies examining the relationship between copper and bone are rare, both in humans and animals. One of the main reasons for this could be the relatively minor prevalence of copper deficiency among most population groups in the United States [34].

Therefore, the aim of this study was to investigate the physiological changes in copper content within the spongy bone of human lumbar vertebrae across different age groups.

Materials and Methods

This study utilized a collection of 211 regular lumbar spine specimens gathered from diseased residents of Luhansk City in Ukraine. The study was approved by the Bioethics Committee of Luhansk State Medical University (3/10112005) and the MPH of Ukraine (2000/20.23.23). The samples of the third lumbar vertebrae (L3) consisted of 106 male and 105 female individuals spanning an age range from 0 to 88 years, with an average age of 40-year-old. All specimens were sourced from individuals who experienced trauma, poisoning, asphyxia, or sudden death due to vascular disorders without spinal damage recorded (Table 1).