An in vivo mouse model of intraosseous spinal cancer causing evolving paraplegia

Abstract

The spine is the commonest site of skeletal metastatic disease and uncontrolled growth of cancer in the spine will inevitably cause pain and neurologic compromise. Improved understanding of the pathobiology behind this devastating condition is urgently needed. For this reason, the aim of this study was to establish a clinically relevant, animal model of spinal cancer. A percutaneous orthotopic injection of human breast (MDA-MB-231) or human prostate (PC-3) cancer cells was administered into the upper lumbar spine of nude mice (n = 6). Animals were monitored twice daily for general welfare, gait asymmetry or disturbance, and hindlimb weakness. After sacrifice, plain radiographs, micro-CT imaging and histological analysis of the spines were performed on each mouse. All mice recovered fully from the inoculation procedure and displayed normal gait and behaviour patterns for at least 3 weeks post-inoculation. Subsequently, between 3 and 5 weeks post-inoculation, each mouse developed evolving paralysis in their hindlimbs over 48-72 h. All followed the same pattern of decline following onset of neurological dysfunction; from gait asymmetry and unilateral hindlimb weakness, to complete unilateral hindlimb paralysis and finally to complete bilateral hindlimb paralysis. Plain radiographs, micro-CT scanning and histological analysis confirmed local tumour growth and destruction of the spine in all six mice. An in vivo mouse model of human intraosseous spinal cancer has been established forming cancers that grow within the spine and cause epidural spinal cord compression, resulting in a reproducible, evolving neurological deficit and paralysis that closely resembles the human condition.

Metastatic human breast cancer to the spine produces mechanical hyperalgesia and gait deficits in rodents

“…In current models the clinical evaluation is done by observational findings or by semi-quantitative rating scales (BBB modified scale) after tumor engraftment, progression of paraparesis until paraplegia [30, 40, 41, 56–58]. In our model we implemented a quantitative methodology to evaluate gait impairment in tumor implanted rats and demonstrated that stride length, velocity and time in the left hind limbs was affected; in some rats the right hind limb had a compensatory role by supporting more weight during locomotion.…”

How to Target Spinal Metastasis in Experimental Research: An Overview of Currently Used Experimental Mouse Models and Future Prospects

“…Subcutaneous [ 38 ] or orthotopic injections at primary site [ 37 ] were used less frequently. Direct implantation methods include methods to implant tumor cell suspensions [ 34 , 36 ] or tumor pieces harvested from carrier animals [ 24 , 35 ] directly into vertebral structures.…”

“…The direct implantation was carried out in four different ways. Tumor cells were implanted through an anterior transabdominal approach into the vertebral body L3 [ 24 ], through a lateral approach into T10 [ 34 ], through a posterolateral percutaneous route into thoracolumbar junctions [ 36 ] or from posterior into the laminae and spinous process [ 35 ]. To carry out the anterior transabdominal inoculation, Tatsui et al identified the left inferior kidney pole as an orientation mark after an abdominal midline incision in supine position [ 24 ].…”

“…Then, with a Hamilton syringe the tumor cell suspension was administered into the vertebral body from lateral, avoiding injury of the spinal cord and -canal [ 34 ]. Cossigny et al immobilized the thoracolumbar junction between the fingers and forceps to inject the tumor cell suspension percutaneously posterolateral into the vertebral body [ 36 ]. For posterior implantation into the laminae and spinous process, Wang et al accessed the bone, preparing muscle and fascia under the microscope to expose the targeted structure [ 35 ].…”

“…Thus, Wang et al concluded a better accessibility from posterior while reducing the risk of neurological injury [ 35 ]. Cossigny et al on the other hand, established the posterolateral approach, which was conducted percutaneously and therefore did not require microdissection [ 36 ]. It must be mentioned that, even if the handling was easy, in the end, a learning curve was needed, resulting in neurological injuries at the beginning [ 35 , 36 ].…”